Joseph Louis Gay-Lussac is best known for putting forward the law of gaseous volumes. Probably this is because it still bears his name, Gay-Lussacs law. He said that when gases combine together their volumes bear a simple ratio to one another if their temperatures and pressure are the same. These volumes also bear a simple ratio to the volumes of the products if these products are gases. If the products are solids or liquids then this does not apply. For example, 2 c.c.s of hydrogen will explode in 1 c.c of oxygen to form 2 c.c.s of steam. These are simple volume ratios. There is no hydrogen or oxygen left over. When the steam condenses to form water, it will occupy a much smaller volume. This was only a small part of Joseph Louis Gay-Lussacs work for he had a very active mind and as well as his discoveries in the field of physics, he made contributions to chemistry and to the chemical industry.

He was born at St. Leonard, a small town in the South of France, and at the age of 19 he entered the Polytechnic School in Paris. On leaving in 1901 he started work for the department of Highways and Bridges. His research work started when he was selected by Berthollet to work as his assistent in the goverment chemical works at Arceuil.

In 1802, as a result of his experiements with gases, he put forward the idea that all gases expand by the same amount of their temperatures are raised by the same amount. This idea was put forward at the same time by Jacques Charles who had been working independently of Joseph Louis Gay-Lussac. Joseph Louis Gay-Lussac also performed experiments to find the coefficient of expansion of gases. That is the volume by which one cubic centimetre of gas would expand if its temperature were raised by one degree centigrade. The value he found was somewhat higher than what is now accepted as the true value.

He then turned his attention to a study of vapours and performed experiments to find the densities of certain of them. He realized that the design of thermometers and barometers was by no meansperfect and spent some time making improvements on them.

Alexander Von Humboldt

Joseph Louis Gay-Lussac wondered how the composition of the atmosphere changed with distance from the earth. How were temperatures affected? How did magnets behave? Such questions led him to make two ascents by balloon to investigate these problems. The second of these ascents he made alone. Together wuth Alexander von Humboldt he analysed a sample of air brought down from 23,000 feet.

Jointly Joseph Louis Gay-Lussac and Humboldt discovered that two volumes of hydrogen combine with one volume of oxygen to form water. This result made Joseph Louis Gay-Lussac wonder if other gases reacted in a similar fashion. In 1808 he had collected enough evidence to show that this was so. Gases did combine in simple volume ratios, and if the products were gases, they too were in simple volume ratios to the reacting gases. On c.c. of nitrogen would combine exactly with 3 c.c.s of hydrogen to form 2 c.c.s of ammonia gas. Joesph Louis Gay-Lussac announced his law in 1808.

In 1809 he was appointed professor of chemistry at the Polytechnic School in Paris where he himself had been a student, and also a professor of chemistry at the Jardin des Plantes. From then on his researches were largely in the field of chemistry. They covered a great many topics. Probably his most important contribution was to industry. Oxides of nitrogen are used as catalysts in the manufacture of sulphuric acid by the lead chamber process. They speed up the reaction; converting sulphur dioxide to the sulphure trioxide which dissolves in water, for sulphuric acid. These oxides can be used over and over again but at the time there was no effective method of recovering these oxides. The first Joseph Louis Gay-Lussac tower for their recovery was used in 1812. Similar towers are still used for the same purpose toda

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