Islamic Inventions 1001
The National Geographic Explorers Hall in Washington is hosting ‘1001 Inventions: Discover the Golden Age of Muslim Civilization' from August 2012 through February 2013. The theme proposes that Muslim civilisation stretched from Spain to China and from the 7th century onwards, men and women of different faiths and cultures built on knowledge from ancient civilisations, making breakthroughs that left their mark on our world and further it seeks to debunk the myth that the dark ages were indeed dark and purports to provide ‘innovations’ that may surprise those, even children, familiar with China, the inventors of paper, Wright Brothers and Yuri Gagarin, amongst others.http://events.nationalgeographic.com/events/exhibits/2012/08/03/1001-inventions/(Advanced appreciation is rendered for materials used without express permission of copyright owners - Tommy Peters)
Content
1A
Paper and pen
Why do you write texts or e-mails? Or keep a diary? Or report on science experiments? People write things down to communicate with others and to record things. Of course, you can only write if you have the tools and materials you need.
Ink
People have used ink for centuries. More than a thousand years ago, Muslims improved ink making techniques. They developed new types of ink, too. Jabir ibn Hayyan made an ink that showed up in the dark. By 1100 CE Ibn Badis was making silver ink by grinding silver filings with distilled wine. He also described making coloured inksÉ and secret writing! Professional scribes used lampblack ink. They made it like this: ¥ Burn linseed oil in a lamp, without much air. The equation shows the products of the reaction. linseed oil + oxygen water + carbon dioxide + carbon monoxide + carbon (from air) The carbon is a black powder Ð soot. ¥ Hold paper or sheepskin above the flame to collect the soot. ¥ Mix the soot with water and gum arabic (sap from an Acacia senegal tree). The soot does not dissolve. Instead, it mixes with the liquids to make a suspension. When you write with this ink, the carbon stays on the surface of the paper. So the writing looks very smooth, and you can wipe it off if you make a mistake. Lampblack ink never fades. Its quality is as good as some modern inks.
The first chapter of the Quran in Jali Diwani style
Pens
For many years, people used specially cut reeds as pens. But there was nowhere to store ink in them, so they werenÕt very convenient. In 953 an Egyptian sultan recorded how his friend, al-MuÕizz, had a creative idea for a new sort of pen: We wish to construct a pen É whose ink will be contained inside it. A person can fill it with ink and write whatever he likes. Within a few days, a craftsman had made a pen just like this. It didnÕt spill ink Ð even when upside down. It didnÕt leave stains on hands or clothes. And it didnÕt need an ink pot because it had its own, hidden away. Al-MuÕizzÕs clever idea, and the craftsmanÕs careful work, meant that people could write with pens containing their own ink, wherever they were. Fountain pens only became common in Europe 900 years later.
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
1A
Paper
Eleven hundred years ago Muslims started making paper in Baghdad. They learnt to make it from some Chinese prisoners: ¥ Make a pulp from the raw material and water. This separates the fibres of the raw material. ¥ Collect the fibres on a mesh. This makes a paper web. ¥ Press the paper web and dry it in air. The Chinese made their paper from mulberry tree bark. The Muslims experimented with other raw materials, including hemp and cotton. Hemp paper was particularly good. The Muslims also made paper from linen rags Ð an early example of recycling! Soon, huge amounts of paper were being made all over the Islamic world. Muslims took their paper-making techniques to many other parts of the world, too. More paper led to cheaper books, so ideas and knowledge spread quickly.
19th century manuscript showing paper making process
Images from Muslim Heritage in our World, FSTC (2006), pages 84 (calligraphy) and 136 (paper making).
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
1B
Ink jet printers
Have you ever used a bubble jet printer? They’ve been around for only 20 years, but now most home computer users wouldn’t want to be without one.
Bubble jet printers store ink in cartridges. When the printer is ready to print, ink moves to the print head. The print head has up to 600 tiny nozzles. Tiny jets of ink come out of these nozzles to make dots on the paper. Each dot is smaller than the diameter of a human hair. And every dot ends up in exactly the right place to make the shapes of the letters and pictures in the document.
How do ink jets come out of the nozzles?
¥ In each nozzle, a tiny electric heater transfers heat to the ink ¥ Next to the heater, a tiny amount of ink vaporizes to make a bubble ¥ The bubble gets bigger. ¥ The expanding bubble pushes ink out of the nozzle. ¥ When the bubble ÔpopsÕ, more ink moves from the cartridge to the print head.
INK BUBBLE THAT GETS BIGGER AND FORCES THE INK OUT OF THE NOZZLE CASING HEATER
Forcing jets of liquid through small holes isnÕt new. More than twelve hundred years ago Banu Musa of Baghdad, Iraq, used sophisticated techniques to make incredible water fountains that directed water in particular directions.
NOZZLE
WhatÕs in ink?
Ink has always been a mixture of a liquid ÔcarrierÕ with dyes or pigments. A thousand years ago, scientists of the Islamic world worked hard to make better and better ink for pens. Now, scientists continue to develop inks for both pens and printers. Most bubble jet printer ink is a mixture of chemicals. The mixture includes: ¥ A pigment to colour the ink. Pigments are tiny crystals. The most important pigment is carbon black. This is the ÔsootÕ made by burning hydrocarbon compounds (like oil or natural gas) without much air. Coloured ink needs coloured pigments. Years ago, these pigments were compounds of metals like lead. Then scientists realised they were poisonous. So they developed safer coloured pigments based on carbon compounds. ¥ A liquid to mix with the pigment crystals and carry them from the ink cartridge and onto the paper. The pigment crystals do not dissolve in the liquid. Water is used most often. A few years ago, other liquids were used. But scientists discovered that some of these cause cancer. So they cannot be added to ink for home use. ¥ Additives to improve the quality of the ink. These include: o Driers to make the ink dry quickly on the paper o Chemicals to stop ink drying on the printer o Biocides to stop micro-organisms living in the ink o Deodorants to cover up bad ink smells
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
2A
Compass
It’s 1900. You’re on a cruise ship, bound for New York. How does the crew make sure you get to the right place? They use a navigational compass, as sailors have done for centuries.
Before compasses, sailors navigated by the Sun and the stars. Some used sounding lines to measure the seaÕs depth, too. This was fine in the seas around the Islamic world, where skies were often clear and waters mostly shallow. But in other places sailors needed a better way of finding their way around. This might explain why the Chinese were probably the first to make and use a compass. The compass is described in a Chinese book of 1044 on military techniques We donÕt know how scientists invented the compass. No-one is sure, either, how the compass got to the Islamic world. But Muslim scientists were quick to use it and improve it. The earliest written evidence of Muslims using the magnetic compass is in Muhammad al-AwfiÕs Collection of Stories. The year was 1233. The voyage was over the Red Sea or the Persian Gulf. The compass was a fish-shaped piece of iron. It worked like this: ¥ Rub the iron fish with a magnetic stone. The iron fish becomes magnetic. ¥ Float the magnetic fish in a bowl of water. The fish rotates until it stops. One end of the fish now points south.
DISH IRON FISH WATER
Of course the other end of the fish magnet points north. This pole is the north-seeking pole. The stone (lodestone) contains magnetic iron oxide, Fe3O4. In 1242, Baylak al-Qibjaqi sailed from Tripoli to Alexandria. He wrote about his journey in The Treasure Book of Merchants in Travels, and included a description of the compass they used. The description is so detailed you can use it to make a compass today. ¥ Make a cross from an iron needle and a rush. ¥ Put the cross in a bowl of water. It floats. ¥ Bring a magnetic stone close to the cross. ¥ Move the stone in a circle above the cross. The cross follows the moving stone. ¥ Suddenly, take the magnetic stone away. The needle will be in a north-south line.
NEEDLE RUSH
WATER
DISH
Reliable compasses meant that Muslims could travel anywhere by boat, without getting lost. So they could trade goods Ð and exchange ideas Ð all over the world. Between 1400 and 1433 the Chinese Muslim Zheng He used compasses on voyages all over the Indian Ocean. He made these journeys before Christopher Columbus was born, on ships five times bigger.
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
2B
SATNAV
Would you like your Mum to know exactly where you are, every second of the day? Well, now she can, if you wear a ‘buddi’ satellite tracking device, invented in 2007 by Sara Murray. You can even get ‘petbuddis’, too!
The buddi relies on the Global Positioning System (GPS). But GPS wasnÕt invented to track teenagers! For many years, the US military used compasses and sextants to navigate Ð just as Muslim sailors had for centuries before them. But in the 1960s, the US military wanted to a method that was quicker and easier to use. They decided to develop a satellite system. The army, air force and navy came up with designs and ideas. By 1973, the best ideas had been incorporated into the final design of NAVSTAR GPS.
Before GPSÉ
More than a thousand years ago, Muslim sailors used astrolabes to pinpoint their position. Meriam al-Ijli, a woman engineer, manufactured many high quality astrolabes in Aleppo-Syria. She died in 967, age 23.
How does NAVSTAR GPS work?
GPS has 24 satellites that orbit 20,000 km above Earth. The satellites transmit radio signals. At any one time, everywhere on Earth receives signals from four or more satellites. The radio signals from a satellite give its position and the time the signal was sent. A receiver picks up the signals. The receiver works out the time taken for a signal to get to it. The receiver knows the speed of the radio signal. So it calculates its distance from the satellite using the equation: distance = speed x time At the same time, the receiver calculates its distance from two other satellites. It uses these distances to work out its location to within a few metres.
How is GPS useful?
The US military originally wanted to keep GPS to itself. It uses GPS to deliver weapons to their exact targets, and for navigation. But in 1983 a South Korean aeroplane flew the wrong way. The plane was shot down, killing all 269 people on board. This tragedy influenced US President ReaganÕs decision to announce that anyone could use GPS. Now, people use GPS to:
¥ ¥ ¥ ¥ ¥
navigate in cars, aeroplanes and boats help in emergency and rescue work find out whatÕs happening in earthquakes track animals for scientific research track offenders, sons, daughters and pets
WhatÕs the future for SATNAV?
In 2007, GPS was the only working satellite navigation system. It is controlled by the US military, who can switch it off at any time. Soon, Europe, India and China will all have their own systems. Ships still have compasses and sextants on board, just like the ones that Muslim sailors used and improved over 1000 years ago. Modern ships use them as a back-up to GPSÉ they donÕt need electricity and the US military canÕt switch them off.
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
3A
Keeping clean
Do you like to smell good and feel clean? If so, you probably use soap! Muslims have been creating sweetly-scented soaps, perfumes and deodorants for more than a thousand years. They made hair dye and curling lotion, too. Europeans began washing regularly with soap less than 300 years ago.
Soap is made in a chemical reaction of an alkali with a fat or oil. There are the remains of an eighth-century soap-making works in Syria. Al-Razi, who died in 925, gives a short recipe for making soap in one of his books. The Arabic word for soap is saboon.
The earliest detailed recipe for soap making is more than 700 years old. It was written down by a Yemeni king. The description is clear enough for someone to use today. The words and pictures summarise the recipe and explain the science behind each step.
BIG CONTAINER WITH HOLE IN THE BOTTOM
Make an alkaline solution
1 2 3 Set up this apparatus. Put wood ash, lime (calcium oxide) and water in the top container. Leave it overnight. The lime, and chemicals from the ash, dissolve to make an alkaline solution. Take the rags out of the hole. The cloth filters the solution. The solution flows into the lower container.
CLOTH SMALL PIECES OF BRICK
React the alkaline solution with sesame oil
4 Add half the solution from stage 3 to an equal volume of sesame oil. 5 Beat the mixture for one hour until it thickens. Leave it for 2-3 days.
BIG CONTAINER IN A HOLE IN THE GROUND
RAGS STUFFED IN THE HOLE
COPPER CAULDRON
6 Put the mixture in a copper cauldron. Heat it over a hot fire. Stir so that it doesnÕt burn. 7 When the mixture thickens, add more alkaline solution from stage 3. Heat it again. Repeat this stage until the soap is a very thick liquid. The chemical reaction is complete.
MIXTURE OF ALKALINE SOLUTION AND SESAME OIL
Mix perfume with the soap
8 Add perfumes to the soap, and saffron to colour it yellow. This makes a mixture. There is no chemical reaction at this stage.
HOT FIRE
Let the soap harden
9 Make a wooden mould. Put a piece of cloth in it. 10 Pour the soap into the cloth. Leave it to harden for a day and a night. 11 Cut the soap into pieces with a knife.
SOAP
PIECE OF CLOTH
WOODEN MOULD
For many years, Muslim traders took soap to Europe, Asia and Africa. It was very valuable. As more people used soap, hygiene and health improved. Today, techniques similar to those of the early Muslims soap-makers are used all over the world.
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
3B
Keeping clean
Are you bothered by body odour? Anxious about acne? Keen to be clean? All good reasons to use soap! Making soap
Soap is made in a chemical reaction of an alkali with a fat or oil: fat + alkali soap + glycerol
LIQUID FAT IN STAINLESS STEEL TOWER
Some modern factories use the process below to make soap:
FATTY ACIDS OUT
¥ Pour liquid fat into 20 metre tall
stainless steel tower. Add very hot water. The fat breaks down to make fatty acids and glycerol. Pump out the fatty acids and the glycerol. Purify the fatty acids by distillation. exact amount of alkali. Stir while the substances react. Pour the liquid soap into a mould. Wait for it to harden.
GLYCEROL OUT
LI ALKA
¥ Mix the purified fatty acids with an
¥ Add fragrance and continue mixing. ¥ Cut the slab into small bars of soap.
MIXTURE OF FATTY ACIDS AND ALKALI
How does soap work?
When you wash, one end of each soap molecule joins to oil, dirt and bacteria. The other end joins to water. So oil, dirt and bacteria get surrounded by waterÉand are easily washed away. Thorough hand-washing with soap and warm water prevents the spread of many diseases.
What about antibacterial soap?
Modern companies want to make money. So they develop new products that people might want. One of these products is antibacterial soap. Armpit sweat contains oils. Bacteria feed on the oils. The bacteria make waste products with pungent smells. This smelly waste is body odour. Antibacterial soaps contain chemicals like triclosan, or alcohols. These chemicals kill bacteria or slow down their growth. So bacteria that cause body odour Ð or disease Ð are removed. But do antibacterial soaps work? Only if you leave them on your skin for two minutes. And some scientists say that antibacterial soaps remove useful bacteria that defend our bodies against disease. So perhaps ordinary soap is just as good at getting us clean and stopping diseases spreadingÉ
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
4A
Diamond, ruby and sapphire
Which of these gemstones would you like to give or receive as a gift? People have enjoyed wearing gemstones for centuries. Muslims living a thousand years ago were no exception. Of course, everyone wanted the most beautiful jewels and to pay fair prices for them. Gemstones are special types of minerals. They are rare, beautiful and hard. The Ancient Egyptians, Greeks and Indians, as well as the Romans, knew a great deal about gemstones. Starting just over a thousand years ago, Muslim scientists continued to build on and extend this knowledge.
Al-Biruni (973 Ð 1050 CE) observed gemstones carefully. He recorded his observations in detail. Al-Biruni also classified gems. He grouped them according to the properties below:
[Rubies] possess different characteristics with respect to brightness of the colour, clarity, glitter, sheen, reflection, and purity from blemishes, and their prices go up according to these characteristics. If scarlet blood is Éspread over a clean piece of silver, the resultant coloration would be like that of the pomegranate-coloured ruby.
¥ Colour ¥ Powder colour ¥ Dispersion (whether white light splits up into the colours of the rainbow when it goes through the gem) ¥ Hardness ¥ Crystal shape ¥ Density
People had studied some of these properties many years earlier. Al-Biruni and other Muslims developed the work of the earlier scientists. Al-Biruni also used combinations of properties to identify gemstones.
Crystal shape
Al-Tifashi studied crystal shape. More than 700 years ago he described diamond crystals: The faces are triangles. If [a diamond] is broken, the faces will be triangular, even at the smallest parts. Two hundred years earlier, Al-Biruni used crystal shape to help him decide whether a gemstone was quartz or diamond.
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
4A
Density
Density is the mass of something in a certain size. Al-Biruni invented a piece of apparatus to measure density. It worked like this:
¥ ¥ ¥ ¥ ¥
Fill the apparatus with water to the mark. Weigh a piece of the mineral and put it in the water. Measure the volume of water that comes out of the pipe end. This is the same as the volume of the mineral. Calculate the density of the mineral. Use the equation density = mass Ö volume.
Al-BiruniÕs results were very accurate. He used them to help him identify minerals.
Name of mineral Ruby Pearl Quartz
Relative density compared to water (water = 1) Al-BiruniÕs result Modern result 4.01 4.40 2.7 2.7 2.58 2.58
Al-BiruniÕs apparatus was based on the work of the Greek scientist Archimedes, who worked out how to use water displacement to measure volume and so calculate density.
Hardness
Hardness is the ability of a mineral to scratch other minerals. The softer mineral is the one that is scratched. Al-Biruni experimented with hardness. He wrote: I have started my book describing diamond before all other gems because it is the leader or master. It scratches corundum and corundum scratches what comes below itÉHowever, corundum cannot scratch diamond. Al-Biruni used hardness to help him identify minerals.
Today, scientists and jewellers still use some of Al-BiruniÕs techniques to identify gemstones. They also use newer techniques and more sophisticated apparatus to help them learn more about gems.
Image above from al-Khazini's Kitab mizan al-hikma, book III, chapter 1, section 2: Hayderabad, al-Uthmaniya University Publications, 1940, p. 59, figure 14.
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
4B
Genuine gems?
Sarah bought a diamond ring. It was cheaper than she expected. Later, she worried the gemstone wasn t genuine. She took it to another jeweller to find out. The jeweller looked at the gemstone. She said it could be diamond, cubic zirconia or Moissanite. Of these three, only diamond is found naturally. The others are manufactured, and are not as valuable.
Scientists have devised many tests to identify gemstones. The jeweller used some of the properties below: ¥ Colour ¥ Powder colour ¥ Dispersion, or ÔfireÕ (how much does white light split up into the colours of the rainbow when it goes through the gemstone?) ¥ Hardness ¥ Crystal shape ¥ Density ¥ Refractive index (how much does the direction of a light ray change when it goes into the gemstone?) ¥ Thermal conductivity (how well does the gemstone conduct heat?) ¥ Electrical conductivity (how well does the gemstone conduct electricity?) ¥ X-ray diffraction (what happens to X-rays when they travel through the gemstone?) Muslims scientists used some of these tests more than a thousand years ago. Scientists developed other tests more recently. For example, scientists could only use refractive index once they had found a way of measuring it. X-ray diffraction could only be used once X-rays were discovered. Apparatus to measure gemstone electrical conductivity quickly was invented after 1998. Before then, there was no need for it as there was no Moissanite jewellery to pass off as diamond!
The jeweller found that SarahÕs gemstone split white light into the colours of the rainbow very well. It conducted heat well. It did not conduct electricity. What was the gemstone?
Diamond When was it first discovered or made? WhatÕs in it? Discovered thousands of years ago The element carbon, C Cubic zirconia Large amounts first made in 1976 The compound zirconium dioxide, ZrO2 Colourless 0.06 8.5-9.0 6.1 2.2 No No Moissanite Gemstones first made in 1998 The compound silicon carbide, SiC Many have a green tinge 0.10 9.0 3.2 2.7 Yes Yes
Colour Dispersion Hardness Density in g/cm3 Refractive index
(biggest value changes light direction most)
Most have a yellow/brown tinge 0.04 10.0 3.6 2.4 Yes No
(biggest value has most ÔfireÕ)
Does it conduct heat well? Does it conduct electricity?
In solving this problem youÕve probably put together several pieces of evidence, just as Muslim experts did when identifying gemstones more than a thousand years ago.
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
5A
Clean air
Have you ever coughed in a smoke-filled room, or breathed in traffic fumes? Not nice! Muslim architects have provided clean air in buildings for centuries.
The Turkish architect Sinan designed more than 80 mosques and 50 schools. His Suleymaniye Mosque, finished in 1557, is magnificent. It is one of the first big public buildings to have a system for supplying fresh air to the people inside it. Sinan knew that the mosque would be lit by hundreds of candles and oil lamps. The equation shows the products of the burning reaction of candle wax:
Suleymaniye Mosque, Istanbul, Turkey
wax +oxygen
(from air)
water + carbon dioxide + carbon monoxide + carbon
The carbon is a fine black powder Ð soot. Normally, convection currents would make the soot spread through the whole mosque. But Sinan didnÕt want the beautifully-decorated inside walls to go black. He didnÕt want worshippers to breathe in dirty air. Also, he didnÕt want to send soot into the city air outside. So Sinan experimented with air currents Ð and thought creatively about his results Ð to make sure the air and the walls stayed clean. One of these experiments apparently involved Sinan sitting in the centre of the unfinished mosque smoking a hubble bubble pipe. Suddenly, Sultan Suleyman, who was paying for the mosque, turned up. He was furious to find Sinan not getting on with his work, and even more furious to find him smoking in a holy place. The Sultan calmed down when Sinan explained that he was testing his newly-designed ventilation systemÉ
A Hubble Bubble Pipe
The ventilation system involved drawing currents of smoky air through a vent and into a small chamber above the entrance hall. Soot was deposited on the chamber walls, and was collected to make ink. The stale air left the building, with very little soot getting to the outside environment. Fresh air came in to replace the polluted air through vents near the floor. So it wasnÕt necessary to open the windows Ð especially on cold winter days. European and North American architects took a while to catch on to lowenergy natural ventilation systems like that of the Suleymaniye Mosque. A similar ventilation system in a 2005 London building is seen as new and exciting.
Image of Sinan from Muslim Heritage in our World, FSTC (2006), page336.
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
5B
Clean air
Have you ever felt sleepy in a hot, stuffy building? Does stale air give you a headache? Air conditioning can solve these problems. But air conditioning runs on electricity. And generating electricity makes greenhouse gases.
The architects designing a university building in London in 2005 were worried about greenhouse gases. So they used natural ventilation to keep the air fresh (and the students awake.) The architects were inspired by WestminsterÕs Central Hall, which was finished in 1912. A huge paddle wheel brought in air through the dome. The air moved down. Then it left the building through big doors and chimneys. So fresh air always filled the building. Nobody knows if the Westminster Hall architects were influenced by Ð or even knew about Ð the similar natural ventilation system in TurkeyÕs Suleymaniye Mosque, built 350 years earlier.
Methodist Central Hall, Westminster, London
The 2005 architects designed a natural ventilation system to keep the new university building cool Ð however hot the weather. They used computer models to help them, and did lots of calculations. The architects made a small-scale model of the building, too. Air enters at the top of the atrium, where it passes through cooling coils. The cool air moves downwards. It supplies air to each floor of the building. This air warms up as it goes through classrooms and offices. Then the warmer air leaves the building.
AIR OUT AIR IN COOLING COILS AIR OUT
ATRIUM
The architects wanted the warm air to leave the building through huge chimneys. They asked a scientist to check whether this would work. The scientist made a see-through model of the building in a water tank. He pumped in coloured fresh and salty water to represent warm and cold air. He filmed the movement of the water through the model to track the airflow through the building. The tests showed up a problem. The natural ventilation system wouldnÕt work on hot days Ð the air was cooler inside than outside so it wouldnÕt go up the chimneys. A building engineer advised the architects to add low-level vents. On hot days, air will exit the building through these vents.
OFFICES AND CLASSROOMS
ATRIUM
Natural ventilation in a new building at University College, London.
The architects have written about the new buildingÕs natural ventilation system in scientific journals and on the Internet. They hope others will be influenced by this Ôenvironmentally-friendlyÕ method of temperature control.
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
6A
Moon
Have you ever marvelled at the Moon’s magnificence? Or wondered why its shape changes? Or considered where it goes when you can’t see it?
People have wondered about the Moon for centuries. Four thousand years ago, Chinese observers recorded lunar eclipses. Around 740 BCE, Babylonians discovered an 18-year pattern of lunar eclipses. At the same time, the Ancient Greeks used calendars based on the cycles of the Moon. Around 500 CE, the Indian astronomer Aryabhata worked out why eclipses happen. At about the same time, Central American observers calculated the phases of the Moon. Muslim astronomy started in earnest in about 800 CE. The astronomers were determined to build on earlier discoveries and learn all they could about this amazing mystery in the sky. They were probably the first to develop the scientific study of astronomy from the non-scientific study of astrology.
Muslims had important reasons to learn about the Moon: ¥ Muslims face Makka when they pray. So they need to know the direction of Makka from everywhere on Earth. ¥ The Muslim calendar depends on the phases of the Moon. Each month begins with the first sighting of the crescent Moon. Muslims wanted to predict when new months would start Ð particularly the holy month of Ramadan. Many Muslim astronomers worked in enormous observatories. One of the worldÕs first observatories opened in Baghdad, Iraq, in 828 CE. The astronomers used huge pieces of apparatus Ð sometimes as long as ten cars end to end Ð to make detailed and accurate observations. One vital piece of apparatus was the astrolabe. Meriam al-Ijli made many of these before she died in 967, aged 23. The astronomers recorded their observations so carefully that astronomers today can still make sense of them. Next the astronomers looked for patterns in their observations. They used the patterns to do calculations and make predictions. One astronomer, Al-Battani, who died in 929 CE, worked out the timings of new Moons. He correctly predicted eclipses many years into the future.
Astronomers at work in an observatory Images from Muslim Heritage in our World, FSTC (2006), pages 289 (observatory) and 303 (lunar eclipse).
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6A
Al-Biruni, who died in 1050 CE, worked out how to use the position of the Sun and Moon to find the direction of Makka from anywhere on Earth. Like the Indian astronomer Aryabhata, who lived 500 years earlier, Al-Biruni interpreted evidence to suggest that the Earth rotates on its own axis. Today, many students are taught that the Polish scientist Copernicus discovered this around the year 1500 CE. Al-Biruni also did calculations to predict the EarthÕs circumference. He did an experiment to check his prediction. This involved taking a camel caravan on a very long walk to measure the distance of a one degree arc of the EarthÕs curvature.
A manuscript showing the lunar eclipse.
Muslim astronomers made many other discoveries. Al-Khujandi calculated the tilt of the Earth. Omar Khyayyam calculated that a year is 365.24219858156 days long. This is correct to the first 6 decimal places. Muslim star maps were used for centuries in Europe and the Far East. Today, more than 165 stars have names based on their original Arabic names, for example ÔAltairÕ, the flying eagle. And modern astronomers still use instruments based on those invented Ð or improved Ð by Muslim astronomers over a thousand years ago.
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
6B
Universe
Have you ever stared at the night sky s stunning stars? Do you wonder where they all come from or where they ll end up? Astronomers have observed, named and mapped the stars for centuries. A thousand years ago, Muslim astronomers used huge instruments in enormous observatories to look at the sky. Recently, curiosity has motivated scientists to develop better and better telescopes. Analysing these observations, and thinking about them creatively, has expanded our understanding of the Universe.
More than 60 years ago, an astronomer had a brilliant idea. How about launching a telescope into space? Without the EarthÕs atmosphere blocking its view, the telescope would see details of stars that had never been seen before. In 1990, space shuttle Discovery launched the Hubble Space Telescope. It began to orbit 600 km above Earth at 16 800 mile/hour. But there was a problem. HubbleÕs huge curved mirror was not curved enough. So Hubble sent blurry images back to Earth. Scientists worked hard to solve the problem. Three years later, astronauts fitted coin-sized mirrors to Hubble. Now the images were much clearer. HubbleÕs real work could begin.
The Hubble Space Telescope
Hubble has solved many astronomical mysteriesÉand created new questions. Through analysing data from Hubble, scientists have learnt more about: ¥ The age of the Universe ¥ How quickly the Universe is expanding Ð and that it is probably getting faster ¥ Black holes Ð and that they are at the centre of most galaxies Hubble has also captured amazing images of exciting events, like JupiterÕs collision with a comet. This event happens once every few centuries
One of the images of cometÕs collision with Jupiter taken by the Hubble Space Telescope
The European Space Agency and NASA run Hubble. Scientists from all over the world ask Hubble to take images. Astronomers publish their findings from Hubble in scientific journals. There are many dramatic images from the telescope on the Internet. In recording and sharing their discoveries, todayÕs astronomers are building on the work of Muslim scientists who produced detailed written records of their findings a thousand years ago.
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© 2007 by the Foundation for Science, Technology and Civilisation (FSTC), UK
7A
Winning smile
Have you ever got food stuck between your teeth? Needed a filling? Had toothache? People have tried to prevent tooth decay for centuries. Muslims have cleaned their teeth regularly for more than 1500 years, and they continue to gargle and wash their mouths before each of the five daily prayers. In Europe, teeth cleaning became common less than 200 years ago. Most Americans only learnt about teeth cleaning when their soldiers returned from Europe in 1945 after the Second World War.
Tooth disease is infectious. Many bacteria live in your mouth Ð including Streptococcus mutans. This type of bacteria causes tooth decay. It sticks to the surface of teeth as plaque. It digests sugars to make lactic acid. The lactic acid dissolves and weakens tooth enamel. So your teeth get holes in them.
This is a miswak twig (left). For many centuries, people have used miswak to clean their teeth. In the sixth century, Prophet Mohammad (pbuh) used miswak before each prayer. He recommended that others use Miswak regularly, too. People cut miswak twigs from the twigs or roots of the Salvadora persica tree. Other trees Ð for example walnut Ð also work well. People probably discovered which were best by trial and error.
Recent research on miswak
Study A Two scientists Ð one from Saudi Arabia and one from the USA Ð studied the effect of miswak on tooth decay bacteria. They recruited 40 male volunteers aged 20 to 45 and put them into four groups: ¥ Ten men cleaned their teeth with miswak twigs ¥ Ten cleaned their teeth with toothbrushes (without toothpaste) ¥ Ten rinsed their mouths with salty water ¥ Ten rinsed their mouths with a solution made from miswak Each person gave a saliva sample before and after cleaning or rinsing.
Streptococcus mutans bacteria
The scientists measured the amount of Streptococcus mutans bacteria in each sample. In all four groups, there was less after cleaning or rinsing. The greatest reduction in the amount of Streptococcus mutans was for men in the miswak twig group. The scientists want to do more research. They hope to study more people for a longer time. They want to add another group and get them to brush with toothpaste. They will take into account how much sugar the volunteers eat, and how healthy their teeth are to start with.
A miswak stick Image of miswak twig from Muslim Heritage in our World, FSTC (2006), pages 23.
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Study B Swedish scientists studied the teeth of 15 people. Each person cleaned their teeth with miswak for three weeks and with a toothbrush for three weeks. The scientists took photos of their teeth. They found that miswak removed more plaque than a toothbrush.
Study C Norwegian scientists wanted to find out which chemicals in miswak destroy tooth-disease bacteria. They found several possibilities, including sodium chloride, potassium chloride and compounds of sulfur and nitrogen. Some reports also claim that miswak contains fluoride compounds, vitamin C and triclosan.
Muslims Ð and others Ð in many parts of the world still clean their teeth with miswak. Modern scientific evidence shows that using miswak is a good way of preventing tooth decay. Miswak has had a huge impact on dental health worldwide.
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7B
Toothpaste
Do you know what’s in your toothpaste? It’s probably a mixture of at least twelve compounds.
Every substance in toothpaste does its own job. Toothpaste companies employ scientists to decide on the best chemical for each job. The scientists work out the quantities to mix together. They make sure the toothpaste tastes and feels good so that people will buy it. They also check that the toothpaste will not harm anyone. Not everyone in the world uses toothpaste. Many Muslims Ð and others Ð clean their teeth with miswak twigs. Several scientific studies show that using miswak is just as effective as Ð or even better than Ð using a toothbrush and toothpaste.
WhatÕs in toothpaste?
Fluoride After every meal, bacteria in your mouth digest sugars to make lactic acid. The acid breaks down tooth enamel. Fluoride works with calcium and phosphate particles in your saliva to make new tooth enamel. So youÕre less likely to get holes in your teeth. The source of fluoride in most toothpaste brands is sodium fluoride.
Abrasives Abrasives scrub away sticky plaque. They help remove food stains, too. At first toothpowders Ð invented by the Egyptians in 5000 BCE Ð contained powdered eggshells and pumice as abrasives. Greek and Roman toothpowders included crushed bones and shells. Around 1000 CE, Persian Muslims warned that hard abrasives damage tooth enamel. Others realised this much later Ð in the 1700s, British toothpowder still contained hard abrasives like brick dust. Modern toothpastes contain less hard abrasives, like silicon dioxide (silica) or titanium dioxide. Detergents and foaming agents Detergents help to clean teeth. They also provide foam to help carry away dirt. Sodium lauryl sulfate is a common toothpaste detergent. Flavourings and sweeteners Early toothpowders contained sugar. When scientists discovered that sugar causes tooth decay, they looked for other sweeteners. Now, many toothpaste brands contain the sweetener sorbitol. Thickeners and binding agents Chemicals like xanthan gum and carageenan thicken toothpastes and bind all the ingredients together. Carageenan comes from red seaweed. Other ingredients Some toothpastes contain substances like triclosan, to kill bacteria. Sensitive teeth toothpastes often contain substances like strontium chloride to block up tiny holes. Whitening toothpastes include compounds like hydrogen peroxide to bleach teeth.
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8A
Pharmacy
Have you ever used tablets, ointments or syrupy medicines? So did the people of Baghdad, Iraq, more than 1100 years ago.
The Muslim pharmacists of ninth century Baghdad were very skilled. They knew how to make, store and preserve a huge variety of medicinal drugs. Most pharmacies were family-run businesses. So parents taught their children all they needed to know to become future pharmacists. The Baghdad pharmacists built on the work of earlier pharmacists from Mesopotamia, Egypt, Greece, India and China. They found out about Greek medicines by translating Greek pharmacistsÕ books. They learnt of Chinese medicines when people travelled between China and the Islamic world. They also inherited traditional medicines from the Babylonians and Assyrians.
A 13th century Arabic version of Dioscorides De Materia Medica showing a pharmacy with chemists preparing medications.
A thousand years ago, expert Muslim pharmacists knew of more than 700 medicines. Ibn Sina listed them all alphabetically in a book, and described the uses of each one. Other scientists listed medicines, too. Many books about medicines include reports of personal observations and experiments. Al-BiruniÕs book mentions the findings of other scientists, and shows that they donÕt always agree! Several of these early books were translated from Arabic into Latin. Because the books were so well organised, they were easy to use. And because they were based on observation and experiment, they were reliable. The books influenced European pharmacists for centuries.
Manuscript with pharmacological tables ascribed to Ibn al-Baytar.
Today, there are lots of different ways of taking the medicines you need. The same was true in the Islamic world: syrups, tablets, capsules and ointments were all available. Pharmacists also mixed bitter-tasting powders with honey or jam to make them taste better. Al-Zahrawi knew that, when taking a mixture of powdered medicines, it was no use just mixing the powders in a bottle. The lighter particles would go to the top, and the heavier ones to the bottom. The patient would get the wrong dose of both medicines. So Al-Zahrawi made tablets from powder mixtures. He wrapped single doses of mixed powders in silver foil, too. Al-Zahrawi also experimented with catgut. As a surgeon, he had used it to stitch up internal organs. As the wound healed, the catgut broke down and dissolved away without infection. He tried wrapping single doses of mixed powdered medicines in catgut. Patients swallowed the catgut parcels. The parcels slowly disintegrated in their stomachs. This released the medicines inside them.
It is vital to get the dose of a medicine correct! The Muslim scientist Al-Kindi realised this more than a thousand years ago. He did lots of calculations to work out medicine doses. Al-Kindi was one of the first scientists to use maths in science. A thousand years ago Ð just as today Ð some medicines were very expensive. Others werenÕt always available. So Al-Kindi looked for Ð and wrote lists of Ð alternative medicines that people could use instead. Today, there are often several alternative medicines for treating an illness. And doctors often look at the cost before deciding which to prescribe.
Muslim doctors did not rely only on medicines. They also prescribed special foods and diets to prevent and treat illnesses Ð just like doctors today. A thousand years ago, Ibn Al-Adeem wrote detailed instructions for 3000 of these recipes.
Images from Muslim Heritage in our World, FSTC (2006), pages 184 (top left) and 187 (lower left).
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8B
Pharmacy 2
Do you find it easy to swallow tablets, or do you prefer to take liquid medicines or have injections?
The way a medicinal drug gets into your body affects how well it works. Muslim pharmacists knew this more than a thousand years ago. ThatÕs why they made tablets, capsules, syrups and ointments. Scientists in pharmaceutical companies continue to improve drug delivery. They want to make sure that a drug gets to the right part of your body at the right time.
People with ADHD (Attention Deficit Hyperactivity Disorder) find it hard to concentrate. They are often restless and impulsive. They may be forgetful and disorganised. Many people with ADHD do not need medicines. They can learn to manage their condition. But some doctors recommend taking medicines like Ritalin or Concerta. Many people with ADHD take three doses of tablets every day. But itÕs hard to remember to take tablets at school. Some people feel embarrassed taking Ritalin, too. So a pharmaceutical company decided to develop a drug that lasted all day. People with ADHD would need just one tablet. They could take it in the morning before school.
First, scientists made a tablet that released its active ingredient gradually, all day. The concentration of the drug in the bloodstream was always the same. But this didnÕt work well. The body gets used to the drug being in the body, and stops responding to it. So the scientists realised they needed a drug that released its ingredients into the blood in short ÔburstsÕÉ just like having separate doses of the drug. The capsule they devised has several layers:
¥ The first layer is a Ôdrug overcoatÕ. It dissolves quickly and gets into the bloodstream fast. ¥ The inner layers push the drug out gradually through a tiny hole. For the next eight hours, small amounts
of the drug come out of the hole. So the concentration of the drug in the bloodstream changes all the time. Other scientists worked out a different system. They put tiny amounts of the drug in separate ÔbeadsÕ. Then they put the beads in a capsule. The coating on some of the beads dissolves quickly. The drug from these beads gets into the bloodstream quickly. The coating on the other beads dissolves slowly. These beads deliver the drug to the bloodstream during the whole school day.
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Paper and pen
Why do you write texts or e-mails? Or keep a diary? Or report on science experiments? People write things down to communicate with others and to record things. Of course, you can only write if you have the tools and materials you need.
Ink
People have used ink for centuries. More than a thousand years ago, Muslims improved ink making techniques. They developed new types of ink, too. Jabir ibn Hayyan made an ink that showed up in the dark. By 1100 CE Ibn Badis was making silver ink by grinding silver filings with distilled wine. He also described making coloured inksÉ and secret writing! Professional scribes used lampblack ink. They made it like this: ¥ Burn linseed oil in a lamp, without much air. The equation shows the products of the reaction. linseed oil + oxygen water + carbon dioxide + carbon monoxide + carbon (from air) The carbon is a black powder Ð soot. ¥ Hold paper or sheepskin above the flame to collect the soot. ¥ Mix the soot with water and gum arabic (sap from an Acacia senegal tree). The soot does not dissolve. Instead, it mixes with the liquids to make a suspension. When you write with this ink, the carbon stays on the surface of the paper. So the writing looks very smooth, and you can wipe it off if you make a mistake. Lampblack ink never fades. Its quality is as good as some modern inks.
The first chapter of the Quran in Jali Diwani style
Pens
For many years, people used specially cut reeds as pens. But there was nowhere to store ink in them, so they werenÕt very convenient. In 953 an Egyptian sultan recorded how his friend, al-MuÕizz, had a creative idea for a new sort of pen: We wish to construct a pen É whose ink will be contained inside it. A person can fill it with ink and write whatever he likes. Within a few days, a craftsman had made a pen just like this. It didnÕt spill ink Ð even when upside down. It didnÕt leave stains on hands or clothes. And it didnÕt need an ink pot because it had its own, hidden away. Al-MuÕizzÕs clever idea, and the craftsmanÕs careful work, meant that people could write with pens containing their own ink, wherever they were. Fountain pens only became common in Europe 900 years later.
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1A
Paper
Eleven hundred years ago Muslims started making paper in Baghdad. They learnt to make it from some Chinese prisoners: ¥ Make a pulp from the raw material and water. This separates the fibres of the raw material. ¥ Collect the fibres on a mesh. This makes a paper web. ¥ Press the paper web and dry it in air. The Chinese made their paper from mulberry tree bark. The Muslims experimented with other raw materials, including hemp and cotton. Hemp paper was particularly good. The Muslims also made paper from linen rags Ð an early example of recycling! Soon, huge amounts of paper were being made all over the Islamic world. Muslims took their paper-making techniques to many other parts of the world, too. More paper led to cheaper books, so ideas and knowledge spread quickly.
19th century manuscript showing paper making process
Images from Muslim Heritage in our World, FSTC (2006), pages 84 (calligraphy) and 136 (paper making).
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1B
Ink jet printers
Have you ever used a bubble jet printer? They’ve been around for only 20 years, but now most home computer users wouldn’t want to be without one.
Bubble jet printers store ink in cartridges. When the printer is ready to print, ink moves to the print head. The print head has up to 600 tiny nozzles. Tiny jets of ink come out of these nozzles to make dots on the paper. Each dot is smaller than the diameter of a human hair. And every dot ends up in exactly the right place to make the shapes of the letters and pictures in the document.
How do ink jets come out of the nozzles?
¥ In each nozzle, a tiny electric heater transfers heat to the ink ¥ Next to the heater, a tiny amount of ink vaporizes to make a bubble ¥ The bubble gets bigger. ¥ The expanding bubble pushes ink out of the nozzle. ¥ When the bubble ÔpopsÕ, more ink moves from the cartridge to the print head.
INK BUBBLE THAT GETS BIGGER AND FORCES THE INK OUT OF THE NOZZLE CASING HEATER
Forcing jets of liquid through small holes isnÕt new. More than twelve hundred years ago Banu Musa of Baghdad, Iraq, used sophisticated techniques to make incredible water fountains that directed water in particular directions.
NOZZLE
WhatÕs in ink?
Ink has always been a mixture of a liquid ÔcarrierÕ with dyes or pigments. A thousand years ago, scientists of the Islamic world worked hard to make better and better ink for pens. Now, scientists continue to develop inks for both pens and printers. Most bubble jet printer ink is a mixture of chemicals. The mixture includes: ¥ A pigment to colour the ink. Pigments are tiny crystals. The most important pigment is carbon black. This is the ÔsootÕ made by burning hydrocarbon compounds (like oil or natural gas) without much air. Coloured ink needs coloured pigments. Years ago, these pigments were compounds of metals like lead. Then scientists realised they were poisonous. So they developed safer coloured pigments based on carbon compounds. ¥ A liquid to mix with the pigment crystals and carry them from the ink cartridge and onto the paper. The pigment crystals do not dissolve in the liquid. Water is used most often. A few years ago, other liquids were used. But scientists discovered that some of these cause cancer. So they cannot be added to ink for home use. ¥ Additives to improve the quality of the ink. These include: o Driers to make the ink dry quickly on the paper o Chemicals to stop ink drying on the printer o Biocides to stop micro-organisms living in the ink o Deodorants to cover up bad ink smells
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2A
Compass
It’s 1900. You’re on a cruise ship, bound for New York. How does the crew make sure you get to the right place? They use a navigational compass, as sailors have done for centuries.
Before compasses, sailors navigated by the Sun and the stars. Some used sounding lines to measure the seaÕs depth, too. This was fine in the seas around the Islamic world, where skies were often clear and waters mostly shallow. But in other places sailors needed a better way of finding their way around. This might explain why the Chinese were probably the first to make and use a compass. The compass is described in a Chinese book of 1044 on military techniques We donÕt know how scientists invented the compass. No-one is sure, either, how the compass got to the Islamic world. But Muslim scientists were quick to use it and improve it. The earliest written evidence of Muslims using the magnetic compass is in Muhammad al-AwfiÕs Collection of Stories. The year was 1233. The voyage was over the Red Sea or the Persian Gulf. The compass was a fish-shaped piece of iron. It worked like this: ¥ Rub the iron fish with a magnetic stone. The iron fish becomes magnetic. ¥ Float the magnetic fish in a bowl of water. The fish rotates until it stops. One end of the fish now points south.
DISH IRON FISH WATER
Of course the other end of the fish magnet points north. This pole is the north-seeking pole. The stone (lodestone) contains magnetic iron oxide, Fe3O4. In 1242, Baylak al-Qibjaqi sailed from Tripoli to Alexandria. He wrote about his journey in The Treasure Book of Merchants in Travels, and included a description of the compass they used. The description is so detailed you can use it to make a compass today. ¥ Make a cross from an iron needle and a rush. ¥ Put the cross in a bowl of water. It floats. ¥ Bring a magnetic stone close to the cross. ¥ Move the stone in a circle above the cross. The cross follows the moving stone. ¥ Suddenly, take the magnetic stone away. The needle will be in a north-south line.
NEEDLE RUSH
WATER
DISH
Reliable compasses meant that Muslims could travel anywhere by boat, without getting lost. So they could trade goods Ð and exchange ideas Ð all over the world. Between 1400 and 1433 the Chinese Muslim Zheng He used compasses on voyages all over the Indian Ocean. He made these journeys before Christopher Columbus was born, on ships five times bigger.
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SATNAV
Would you like your Mum to know exactly where you are, every second of the day? Well, now she can, if you wear a ‘buddi’ satellite tracking device, invented in 2007 by Sara Murray. You can even get ‘petbuddis’, too!
The buddi relies on the Global Positioning System (GPS). But GPS wasnÕt invented to track teenagers! For many years, the US military used compasses and sextants to navigate Ð just as Muslim sailors had for centuries before them. But in the 1960s, the US military wanted to a method that was quicker and easier to use. They decided to develop a satellite system. The army, air force and navy came up with designs and ideas. By 1973, the best ideas had been incorporated into the final design of NAVSTAR GPS.
Before GPSÉ
More than a thousand years ago, Muslim sailors used astrolabes to pinpoint their position. Meriam al-Ijli, a woman engineer, manufactured many high quality astrolabes in Aleppo-Syria. She died in 967, age 23.
How does NAVSTAR GPS work?
GPS has 24 satellites that orbit 20,000 km above Earth. The satellites transmit radio signals. At any one time, everywhere on Earth receives signals from four or more satellites. The radio signals from a satellite give its position and the time the signal was sent. A receiver picks up the signals. The receiver works out the time taken for a signal to get to it. The receiver knows the speed of the radio signal. So it calculates its distance from the satellite using the equation: distance = speed x time At the same time, the receiver calculates its distance from two other satellites. It uses these distances to work out its location to within a few metres.
How is GPS useful?
The US military originally wanted to keep GPS to itself. It uses GPS to deliver weapons to their exact targets, and for navigation. But in 1983 a South Korean aeroplane flew the wrong way. The plane was shot down, killing all 269 people on board. This tragedy influenced US President ReaganÕs decision to announce that anyone could use GPS. Now, people use GPS to:
¥ ¥ ¥ ¥ ¥
navigate in cars, aeroplanes and boats help in emergency and rescue work find out whatÕs happening in earthquakes track animals for scientific research track offenders, sons, daughters and pets
WhatÕs the future for SATNAV?
In 2007, GPS was the only working satellite navigation system. It is controlled by the US military, who can switch it off at any time. Soon, Europe, India and China will all have their own systems. Ships still have compasses and sextants on board, just like the ones that Muslim sailors used and improved over 1000 years ago. Modern ships use them as a back-up to GPSÉ they donÕt need electricity and the US military canÕt switch them off.
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3A
Keeping clean
Do you like to smell good and feel clean? If so, you probably use soap! Muslims have been creating sweetly-scented soaps, perfumes and deodorants for more than a thousand years. They made hair dye and curling lotion, too. Europeans began washing regularly with soap less than 300 years ago.
Soap is made in a chemical reaction of an alkali with a fat or oil. There are the remains of an eighth-century soap-making works in Syria. Al-Razi, who died in 925, gives a short recipe for making soap in one of his books. The Arabic word for soap is saboon.
The earliest detailed recipe for soap making is more than 700 years old. It was written down by a Yemeni king. The description is clear enough for someone to use today. The words and pictures summarise the recipe and explain the science behind each step.
BIG CONTAINER WITH HOLE IN THE BOTTOM
Make an alkaline solution
1 2 3 Set up this apparatus. Put wood ash, lime (calcium oxide) and water in the top container. Leave it overnight. The lime, and chemicals from the ash, dissolve to make an alkaline solution. Take the rags out of the hole. The cloth filters the solution. The solution flows into the lower container.
CLOTH SMALL PIECES OF BRICK
React the alkaline solution with sesame oil
4 Add half the solution from stage 3 to an equal volume of sesame oil. 5 Beat the mixture for one hour until it thickens. Leave it for 2-3 days.
BIG CONTAINER IN A HOLE IN THE GROUND
RAGS STUFFED IN THE HOLE
COPPER CAULDRON
6 Put the mixture in a copper cauldron. Heat it over a hot fire. Stir so that it doesnÕt burn. 7 When the mixture thickens, add more alkaline solution from stage 3. Heat it again. Repeat this stage until the soap is a very thick liquid. The chemical reaction is complete.
MIXTURE OF ALKALINE SOLUTION AND SESAME OIL
Mix perfume with the soap
8 Add perfumes to the soap, and saffron to colour it yellow. This makes a mixture. There is no chemical reaction at this stage.
HOT FIRE
Let the soap harden
9 Make a wooden mould. Put a piece of cloth in it. 10 Pour the soap into the cloth. Leave it to harden for a day and a night. 11 Cut the soap into pieces with a knife.
SOAP
PIECE OF CLOTH
WOODEN MOULD
For many years, Muslim traders took soap to Europe, Asia and Africa. It was very valuable. As more people used soap, hygiene and health improved. Today, techniques similar to those of the early Muslims soap-makers are used all over the world.
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3B
Keeping clean
Are you bothered by body odour? Anxious about acne? Keen to be clean? All good reasons to use soap! Making soap
Soap is made in a chemical reaction of an alkali with a fat or oil: fat + alkali soap + glycerol
LIQUID FAT IN STAINLESS STEEL TOWER
Some modern factories use the process below to make soap:
FATTY ACIDS OUT
¥ Pour liquid fat into 20 metre tall
stainless steel tower. Add very hot water. The fat breaks down to make fatty acids and glycerol. Pump out the fatty acids and the glycerol. Purify the fatty acids by distillation. exact amount of alkali. Stir while the substances react. Pour the liquid soap into a mould. Wait for it to harden.
GLYCEROL OUT
LI ALKA
¥ Mix the purified fatty acids with an
¥ Add fragrance and continue mixing. ¥ Cut the slab into small bars of soap.
MIXTURE OF FATTY ACIDS AND ALKALI
How does soap work?
When you wash, one end of each soap molecule joins to oil, dirt and bacteria. The other end joins to water. So oil, dirt and bacteria get surrounded by waterÉand are easily washed away. Thorough hand-washing with soap and warm water prevents the spread of many diseases.
What about antibacterial soap?
Modern companies want to make money. So they develop new products that people might want. One of these products is antibacterial soap. Armpit sweat contains oils. Bacteria feed on the oils. The bacteria make waste products with pungent smells. This smelly waste is body odour. Antibacterial soaps contain chemicals like triclosan, or alcohols. These chemicals kill bacteria or slow down their growth. So bacteria that cause body odour Ð or disease Ð are removed. But do antibacterial soaps work? Only if you leave them on your skin for two minutes. And some scientists say that antibacterial soaps remove useful bacteria that defend our bodies against disease. So perhaps ordinary soap is just as good at getting us clean and stopping diseases spreadingÉ
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4A
Diamond, ruby and sapphire
Which of these gemstones would you like to give or receive as a gift? People have enjoyed wearing gemstones for centuries. Muslims living a thousand years ago were no exception. Of course, everyone wanted the most beautiful jewels and to pay fair prices for them. Gemstones are special types of minerals. They are rare, beautiful and hard. The Ancient Egyptians, Greeks and Indians, as well as the Romans, knew a great deal about gemstones. Starting just over a thousand years ago, Muslim scientists continued to build on and extend this knowledge.
Al-Biruni (973 Ð 1050 CE) observed gemstones carefully. He recorded his observations in detail. Al-Biruni also classified gems. He grouped them according to the properties below:
[Rubies] possess different characteristics with respect to brightness of the colour, clarity, glitter, sheen, reflection, and purity from blemishes, and their prices go up according to these characteristics. If scarlet blood is Éspread over a clean piece of silver, the resultant coloration would be like that of the pomegranate-coloured ruby.
¥ Colour ¥ Powder colour ¥ Dispersion (whether white light splits up into the colours of the rainbow when it goes through the gem) ¥ Hardness ¥ Crystal shape ¥ Density
People had studied some of these properties many years earlier. Al-Biruni and other Muslims developed the work of the earlier scientists. Al-Biruni also used combinations of properties to identify gemstones.
Crystal shape
Al-Tifashi studied crystal shape. More than 700 years ago he described diamond crystals: The faces are triangles. If [a diamond] is broken, the faces will be triangular, even at the smallest parts. Two hundred years earlier, Al-Biruni used crystal shape to help him decide whether a gemstone was quartz or diamond.
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4A
Density
Density is the mass of something in a certain size. Al-Biruni invented a piece of apparatus to measure density. It worked like this:
¥ ¥ ¥ ¥ ¥
Fill the apparatus with water to the mark. Weigh a piece of the mineral and put it in the water. Measure the volume of water that comes out of the pipe end. This is the same as the volume of the mineral. Calculate the density of the mineral. Use the equation density = mass Ö volume.
Al-BiruniÕs results were very accurate. He used them to help him identify minerals.
Name of mineral Ruby Pearl Quartz
Relative density compared to water (water = 1) Al-BiruniÕs result Modern result 4.01 4.40 2.7 2.7 2.58 2.58
Al-BiruniÕs apparatus was based on the work of the Greek scientist Archimedes, who worked out how to use water displacement to measure volume and so calculate density.
Hardness
Hardness is the ability of a mineral to scratch other minerals. The softer mineral is the one that is scratched. Al-Biruni experimented with hardness. He wrote: I have started my book describing diamond before all other gems because it is the leader or master. It scratches corundum and corundum scratches what comes below itÉHowever, corundum cannot scratch diamond. Al-Biruni used hardness to help him identify minerals.
Today, scientists and jewellers still use some of Al-BiruniÕs techniques to identify gemstones. They also use newer techniques and more sophisticated apparatus to help them learn more about gems.
Image above from al-Khazini's Kitab mizan al-hikma, book III, chapter 1, section 2: Hayderabad, al-Uthmaniya University Publications, 1940, p. 59, figure 14.
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4B
Genuine gems?
Sarah bought a diamond ring. It was cheaper than she expected. Later, she worried the gemstone wasn t genuine. She took it to another jeweller to find out. The jeweller looked at the gemstone. She said it could be diamond, cubic zirconia or Moissanite. Of these three, only diamond is found naturally. The others are manufactured, and are not as valuable.
Scientists have devised many tests to identify gemstones. The jeweller used some of the properties below: ¥ Colour ¥ Powder colour ¥ Dispersion, or ÔfireÕ (how much does white light split up into the colours of the rainbow when it goes through the gemstone?) ¥ Hardness ¥ Crystal shape ¥ Density ¥ Refractive index (how much does the direction of a light ray change when it goes into the gemstone?) ¥ Thermal conductivity (how well does the gemstone conduct heat?) ¥ Electrical conductivity (how well does the gemstone conduct electricity?) ¥ X-ray diffraction (what happens to X-rays when they travel through the gemstone?) Muslims scientists used some of these tests more than a thousand years ago. Scientists developed other tests more recently. For example, scientists could only use refractive index once they had found a way of measuring it. X-ray diffraction could only be used once X-rays were discovered. Apparatus to measure gemstone electrical conductivity quickly was invented after 1998. Before then, there was no need for it as there was no Moissanite jewellery to pass off as diamond!
The jeweller found that SarahÕs gemstone split white light into the colours of the rainbow very well. It conducted heat well. It did not conduct electricity. What was the gemstone?
Diamond When was it first discovered or made? WhatÕs in it? Discovered thousands of years ago The element carbon, C Cubic zirconia Large amounts first made in 1976 The compound zirconium dioxide, ZrO2 Colourless 0.06 8.5-9.0 6.1 2.2 No No Moissanite Gemstones first made in 1998 The compound silicon carbide, SiC Many have a green tinge 0.10 9.0 3.2 2.7 Yes Yes
Colour Dispersion Hardness Density in g/cm3 Refractive index
(biggest value changes light direction most)
Most have a yellow/brown tinge 0.04 10.0 3.6 2.4 Yes No
(biggest value has most ÔfireÕ)
Does it conduct heat well? Does it conduct electricity?
In solving this problem youÕve probably put together several pieces of evidence, just as Muslim experts did when identifying gemstones more than a thousand years ago.
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5A
Clean air
Have you ever coughed in a smoke-filled room, or breathed in traffic fumes? Not nice! Muslim architects have provided clean air in buildings for centuries.
The Turkish architect Sinan designed more than 80 mosques and 50 schools. His Suleymaniye Mosque, finished in 1557, is magnificent. It is one of the first big public buildings to have a system for supplying fresh air to the people inside it. Sinan knew that the mosque would be lit by hundreds of candles and oil lamps. The equation shows the products of the burning reaction of candle wax:
Suleymaniye Mosque, Istanbul, Turkey
wax +oxygen
(from air)
water + carbon dioxide + carbon monoxide + carbon
The carbon is a fine black powder Ð soot. Normally, convection currents would make the soot spread through the whole mosque. But Sinan didnÕt want the beautifully-decorated inside walls to go black. He didnÕt want worshippers to breathe in dirty air. Also, he didnÕt want to send soot into the city air outside. So Sinan experimented with air currents Ð and thought creatively about his results Ð to make sure the air and the walls stayed clean. One of these experiments apparently involved Sinan sitting in the centre of the unfinished mosque smoking a hubble bubble pipe. Suddenly, Sultan Suleyman, who was paying for the mosque, turned up. He was furious to find Sinan not getting on with his work, and even more furious to find him smoking in a holy place. The Sultan calmed down when Sinan explained that he was testing his newly-designed ventilation systemÉ
A Hubble Bubble Pipe
The ventilation system involved drawing currents of smoky air through a vent and into a small chamber above the entrance hall. Soot was deposited on the chamber walls, and was collected to make ink. The stale air left the building, with very little soot getting to the outside environment. Fresh air came in to replace the polluted air through vents near the floor. So it wasnÕt necessary to open the windows Ð especially on cold winter days. European and North American architects took a while to catch on to lowenergy natural ventilation systems like that of the Suleymaniye Mosque. A similar ventilation system in a 2005 London building is seen as new and exciting.
Image of Sinan from Muslim Heritage in our World, FSTC (2006), page336.
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5B
Clean air
Have you ever felt sleepy in a hot, stuffy building? Does stale air give you a headache? Air conditioning can solve these problems. But air conditioning runs on electricity. And generating electricity makes greenhouse gases.
The architects designing a university building in London in 2005 were worried about greenhouse gases. So they used natural ventilation to keep the air fresh (and the students awake.) The architects were inspired by WestminsterÕs Central Hall, which was finished in 1912. A huge paddle wheel brought in air through the dome. The air moved down. Then it left the building through big doors and chimneys. So fresh air always filled the building. Nobody knows if the Westminster Hall architects were influenced by Ð or even knew about Ð the similar natural ventilation system in TurkeyÕs Suleymaniye Mosque, built 350 years earlier.
Methodist Central Hall, Westminster, London
The 2005 architects designed a natural ventilation system to keep the new university building cool Ð however hot the weather. They used computer models to help them, and did lots of calculations. The architects made a small-scale model of the building, too. Air enters at the top of the atrium, where it passes through cooling coils. The cool air moves downwards. It supplies air to each floor of the building. This air warms up as it goes through classrooms and offices. Then the warmer air leaves the building.
AIR OUT AIR IN COOLING COILS AIR OUT
ATRIUM
The architects wanted the warm air to leave the building through huge chimneys. They asked a scientist to check whether this would work. The scientist made a see-through model of the building in a water tank. He pumped in coloured fresh and salty water to represent warm and cold air. He filmed the movement of the water through the model to track the airflow through the building. The tests showed up a problem. The natural ventilation system wouldnÕt work on hot days Ð the air was cooler inside than outside so it wouldnÕt go up the chimneys. A building engineer advised the architects to add low-level vents. On hot days, air will exit the building through these vents.
OFFICES AND CLASSROOMS
ATRIUM
Natural ventilation in a new building at University College, London.
The architects have written about the new buildingÕs natural ventilation system in scientific journals and on the Internet. They hope others will be influenced by this Ôenvironmentally-friendlyÕ method of temperature control.
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6A
Moon
Have you ever marvelled at the Moon’s magnificence? Or wondered why its shape changes? Or considered where it goes when you can’t see it?
People have wondered about the Moon for centuries. Four thousand years ago, Chinese observers recorded lunar eclipses. Around 740 BCE, Babylonians discovered an 18-year pattern of lunar eclipses. At the same time, the Ancient Greeks used calendars based on the cycles of the Moon. Around 500 CE, the Indian astronomer Aryabhata worked out why eclipses happen. At about the same time, Central American observers calculated the phases of the Moon. Muslim astronomy started in earnest in about 800 CE. The astronomers were determined to build on earlier discoveries and learn all they could about this amazing mystery in the sky. They were probably the first to develop the scientific study of astronomy from the non-scientific study of astrology.
Muslims had important reasons to learn about the Moon: ¥ Muslims face Makka when they pray. So they need to know the direction of Makka from everywhere on Earth. ¥ The Muslim calendar depends on the phases of the Moon. Each month begins with the first sighting of the crescent Moon. Muslims wanted to predict when new months would start Ð particularly the holy month of Ramadan. Many Muslim astronomers worked in enormous observatories. One of the worldÕs first observatories opened in Baghdad, Iraq, in 828 CE. The astronomers used huge pieces of apparatus Ð sometimes as long as ten cars end to end Ð to make detailed and accurate observations. One vital piece of apparatus was the astrolabe. Meriam al-Ijli made many of these before she died in 967, aged 23. The astronomers recorded their observations so carefully that astronomers today can still make sense of them. Next the astronomers looked for patterns in their observations. They used the patterns to do calculations and make predictions. One astronomer, Al-Battani, who died in 929 CE, worked out the timings of new Moons. He correctly predicted eclipses many years into the future.
Astronomers at work in an observatory Images from Muslim Heritage in our World, FSTC (2006), pages 289 (observatory) and 303 (lunar eclipse).
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6A
Al-Biruni, who died in 1050 CE, worked out how to use the position of the Sun and Moon to find the direction of Makka from anywhere on Earth. Like the Indian astronomer Aryabhata, who lived 500 years earlier, Al-Biruni interpreted evidence to suggest that the Earth rotates on its own axis. Today, many students are taught that the Polish scientist Copernicus discovered this around the year 1500 CE. Al-Biruni also did calculations to predict the EarthÕs circumference. He did an experiment to check his prediction. This involved taking a camel caravan on a very long walk to measure the distance of a one degree arc of the EarthÕs curvature.
A manuscript showing the lunar eclipse.
Muslim astronomers made many other discoveries. Al-Khujandi calculated the tilt of the Earth. Omar Khyayyam calculated that a year is 365.24219858156 days long. This is correct to the first 6 decimal places. Muslim star maps were used for centuries in Europe and the Far East. Today, more than 165 stars have names based on their original Arabic names, for example ÔAltairÕ, the flying eagle. And modern astronomers still use instruments based on those invented Ð or improved Ð by Muslim astronomers over a thousand years ago.
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6B
Universe
Have you ever stared at the night sky s stunning stars? Do you wonder where they all come from or where they ll end up? Astronomers have observed, named and mapped the stars for centuries. A thousand years ago, Muslim astronomers used huge instruments in enormous observatories to look at the sky. Recently, curiosity has motivated scientists to develop better and better telescopes. Analysing these observations, and thinking about them creatively, has expanded our understanding of the Universe.
More than 60 years ago, an astronomer had a brilliant idea. How about launching a telescope into space? Without the EarthÕs atmosphere blocking its view, the telescope would see details of stars that had never been seen before. In 1990, space shuttle Discovery launched the Hubble Space Telescope. It began to orbit 600 km above Earth at 16 800 mile/hour. But there was a problem. HubbleÕs huge curved mirror was not curved enough. So Hubble sent blurry images back to Earth. Scientists worked hard to solve the problem. Three years later, astronauts fitted coin-sized mirrors to Hubble. Now the images were much clearer. HubbleÕs real work could begin.
The Hubble Space Telescope
Hubble has solved many astronomical mysteriesÉand created new questions. Through analysing data from Hubble, scientists have learnt more about: ¥ The age of the Universe ¥ How quickly the Universe is expanding Ð and that it is probably getting faster ¥ Black holes Ð and that they are at the centre of most galaxies Hubble has also captured amazing images of exciting events, like JupiterÕs collision with a comet. This event happens once every few centuries
One of the images of cometÕs collision with Jupiter taken by the Hubble Space Telescope
The European Space Agency and NASA run Hubble. Scientists from all over the world ask Hubble to take images. Astronomers publish their findings from Hubble in scientific journals. There are many dramatic images from the telescope on the Internet. In recording and sharing their discoveries, todayÕs astronomers are building on the work of Muslim scientists who produced detailed written records of their findings a thousand years ago.
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7A
Winning smile
Have you ever got food stuck between your teeth? Needed a filling? Had toothache? People have tried to prevent tooth decay for centuries. Muslims have cleaned their teeth regularly for more than 1500 years, and they continue to gargle and wash their mouths before each of the five daily prayers. In Europe, teeth cleaning became common less than 200 years ago. Most Americans only learnt about teeth cleaning when their soldiers returned from Europe in 1945 after the Second World War.
Tooth disease is infectious. Many bacteria live in your mouth Ð including Streptococcus mutans. This type of bacteria causes tooth decay. It sticks to the surface of teeth as plaque. It digests sugars to make lactic acid. The lactic acid dissolves and weakens tooth enamel. So your teeth get holes in them.
This is a miswak twig (left). For many centuries, people have used miswak to clean their teeth. In the sixth century, Prophet Mohammad (pbuh) used miswak before each prayer. He recommended that others use Miswak regularly, too. People cut miswak twigs from the twigs or roots of the Salvadora persica tree. Other trees Ð for example walnut Ð also work well. People probably discovered which were best by trial and error.
Recent research on miswak
Study A Two scientists Ð one from Saudi Arabia and one from the USA Ð studied the effect of miswak on tooth decay bacteria. They recruited 40 male volunteers aged 20 to 45 and put them into four groups: ¥ Ten men cleaned their teeth with miswak twigs ¥ Ten cleaned their teeth with toothbrushes (without toothpaste) ¥ Ten rinsed their mouths with salty water ¥ Ten rinsed their mouths with a solution made from miswak Each person gave a saliva sample before and after cleaning or rinsing.
Streptococcus mutans bacteria
The scientists measured the amount of Streptococcus mutans bacteria in each sample. In all four groups, there was less after cleaning or rinsing. The greatest reduction in the amount of Streptococcus mutans was for men in the miswak twig group. The scientists want to do more research. They hope to study more people for a longer time. They want to add another group and get them to brush with toothpaste. They will take into account how much sugar the volunteers eat, and how healthy their teeth are to start with.
A miswak stick Image of miswak twig from Muslim Heritage in our World, FSTC (2006), pages 23.
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7A
Study B Swedish scientists studied the teeth of 15 people. Each person cleaned their teeth with miswak for three weeks and with a toothbrush for three weeks. The scientists took photos of their teeth. They found that miswak removed more plaque than a toothbrush.
Study C Norwegian scientists wanted to find out which chemicals in miswak destroy tooth-disease bacteria. They found several possibilities, including sodium chloride, potassium chloride and compounds of sulfur and nitrogen. Some reports also claim that miswak contains fluoride compounds, vitamin C and triclosan.
Muslims Ð and others Ð in many parts of the world still clean their teeth with miswak. Modern scientific evidence shows that using miswak is a good way of preventing tooth decay. Miswak has had a huge impact on dental health worldwide.
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7B
Toothpaste
Do you know what’s in your toothpaste? It’s probably a mixture of at least twelve compounds.
Every substance in toothpaste does its own job. Toothpaste companies employ scientists to decide on the best chemical for each job. The scientists work out the quantities to mix together. They make sure the toothpaste tastes and feels good so that people will buy it. They also check that the toothpaste will not harm anyone. Not everyone in the world uses toothpaste. Many Muslims Ð and others Ð clean their teeth with miswak twigs. Several scientific studies show that using miswak is just as effective as Ð or even better than Ð using a toothbrush and toothpaste.
WhatÕs in toothpaste?
Fluoride After every meal, bacteria in your mouth digest sugars to make lactic acid. The acid breaks down tooth enamel. Fluoride works with calcium and phosphate particles in your saliva to make new tooth enamel. So youÕre less likely to get holes in your teeth. The source of fluoride in most toothpaste brands is sodium fluoride.
Abrasives Abrasives scrub away sticky plaque. They help remove food stains, too. At first toothpowders Ð invented by the Egyptians in 5000 BCE Ð contained powdered eggshells and pumice as abrasives. Greek and Roman toothpowders included crushed bones and shells. Around 1000 CE, Persian Muslims warned that hard abrasives damage tooth enamel. Others realised this much later Ð in the 1700s, British toothpowder still contained hard abrasives like brick dust. Modern toothpastes contain less hard abrasives, like silicon dioxide (silica) or titanium dioxide. Detergents and foaming agents Detergents help to clean teeth. They also provide foam to help carry away dirt. Sodium lauryl sulfate is a common toothpaste detergent. Flavourings and sweeteners Early toothpowders contained sugar. When scientists discovered that sugar causes tooth decay, they looked for other sweeteners. Now, many toothpaste brands contain the sweetener sorbitol. Thickeners and binding agents Chemicals like xanthan gum and carageenan thicken toothpastes and bind all the ingredients together. Carageenan comes from red seaweed. Other ingredients Some toothpastes contain substances like triclosan, to kill bacteria. Sensitive teeth toothpastes often contain substances like strontium chloride to block up tiny holes. Whitening toothpastes include compounds like hydrogen peroxide to bleach teeth.
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8A
Pharmacy
Have you ever used tablets, ointments or syrupy medicines? So did the people of Baghdad, Iraq, more than 1100 years ago.
The Muslim pharmacists of ninth century Baghdad were very skilled. They knew how to make, store and preserve a huge variety of medicinal drugs. Most pharmacies were family-run businesses. So parents taught their children all they needed to know to become future pharmacists. The Baghdad pharmacists built on the work of earlier pharmacists from Mesopotamia, Egypt, Greece, India and China. They found out about Greek medicines by translating Greek pharmacistsÕ books. They learnt of Chinese medicines when people travelled between China and the Islamic world. They also inherited traditional medicines from the Babylonians and Assyrians.
A 13th century Arabic version of Dioscorides De Materia Medica showing a pharmacy with chemists preparing medications.
A thousand years ago, expert Muslim pharmacists knew of more than 700 medicines. Ibn Sina listed them all alphabetically in a book, and described the uses of each one. Other scientists listed medicines, too. Many books about medicines include reports of personal observations and experiments. Al-BiruniÕs book mentions the findings of other scientists, and shows that they donÕt always agree! Several of these early books were translated from Arabic into Latin. Because the books were so well organised, they were easy to use. And because they were based on observation and experiment, they were reliable. The books influenced European pharmacists for centuries.
Manuscript with pharmacological tables ascribed to Ibn al-Baytar.
Today, there are lots of different ways of taking the medicines you need. The same was true in the Islamic world: syrups, tablets, capsules and ointments were all available. Pharmacists also mixed bitter-tasting powders with honey or jam to make them taste better. Al-Zahrawi knew that, when taking a mixture of powdered medicines, it was no use just mixing the powders in a bottle. The lighter particles would go to the top, and the heavier ones to the bottom. The patient would get the wrong dose of both medicines. So Al-Zahrawi made tablets from powder mixtures. He wrapped single doses of mixed powders in silver foil, too. Al-Zahrawi also experimented with catgut. As a surgeon, he had used it to stitch up internal organs. As the wound healed, the catgut broke down and dissolved away without infection. He tried wrapping single doses of mixed powdered medicines in catgut. Patients swallowed the catgut parcels. The parcels slowly disintegrated in their stomachs. This released the medicines inside them.
It is vital to get the dose of a medicine correct! The Muslim scientist Al-Kindi realised this more than a thousand years ago. He did lots of calculations to work out medicine doses. Al-Kindi was one of the first scientists to use maths in science. A thousand years ago Ð just as today Ð some medicines were very expensive. Others werenÕt always available. So Al-Kindi looked for Ð and wrote lists of Ð alternative medicines that people could use instead. Today, there are often several alternative medicines for treating an illness. And doctors often look at the cost before deciding which to prescribe.
Muslim doctors did not rely only on medicines. They also prescribed special foods and diets to prevent and treat illnesses Ð just like doctors today. A thousand years ago, Ibn Al-Adeem wrote detailed instructions for 3000 of these recipes.
Images from Muslim Heritage in our World, FSTC (2006), pages 184 (top left) and 187 (lower left).
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8B
Pharmacy 2
Do you find it easy to swallow tablets, or do you prefer to take liquid medicines or have injections?
The way a medicinal drug gets into your body affects how well it works. Muslim pharmacists knew this more than a thousand years ago. ThatÕs why they made tablets, capsules, syrups and ointments. Scientists in pharmaceutical companies continue to improve drug delivery. They want to make sure that a drug gets to the right part of your body at the right time.
People with ADHD (Attention Deficit Hyperactivity Disorder) find it hard to concentrate. They are often restless and impulsive. They may be forgetful and disorganised. Many people with ADHD do not need medicines. They can learn to manage their condition. But some doctors recommend taking medicines like Ritalin or Concerta. Many people with ADHD take three doses of tablets every day. But itÕs hard to remember to take tablets at school. Some people feel embarrassed taking Ritalin, too. So a pharmaceutical company decided to develop a drug that lasted all day. People with ADHD would need just one tablet. They could take it in the morning before school.
First, scientists made a tablet that released its active ingredient gradually, all day. The concentration of the drug in the bloodstream was always the same. But this didnÕt work well. The body gets used to the drug being in the body, and stops responding to it. So the scientists realised they needed a drug that released its ingredients into the blood in short ÔburstsÕÉ just like having separate doses of the drug. The capsule they devised has several layers:
¥ The first layer is a Ôdrug overcoatÕ. It dissolves quickly and gets into the bloodstream fast. ¥ The inner layers push the drug out gradually through a tiny hole. For the next eight hours, small amounts
of the drug come out of the hole. So the concentration of the drug in the bloodstream changes all the time. Other scientists worked out a different system. They put tiny amounts of the drug in separate ÔbeadsÕ. Then they put the beads in a capsule. The coating on some of the beads dissolves quickly. The drug from these beads gets into the bloodstream quickly. The coating on the other beads dissolves slowly. These beads deliver the drug to the bloodstream during the whole school day.
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