Thomas Graham (chemist)
Thomas Graham ( born December 21, 1805 in Glasgow, † September 11, 1869 in London) was a British chemist and physical chemist. Graham examined the Strömungsgeswindigkeiten of gases through a very thin hole in a vacuum. The flow rate was inversely proportional to the square root of the molecular weight of the gas. He also determined the diffusion of salts in liquids. Graham has also explores the foundations for the diffusion of substances through a membrane (dialysis), colloids ( macromolecular substances ) could not penetrate the membrane.
Curriculum vitae
Thomas Graham was the son of a successful factory in Glasgow. His father wished that he should become a priest. However, Thomas had no inclination to, he wanted to study science - later it was signified by the rupture of the relationship between father and son. From 1819 he worked on studies of mathematics, physics and chemistry in the University of Glasgow. Graham graduated with a degree in Natural Sciences from the " Master of Arts", but received no financial support from the more wealthy father.
After several poor assistant he became in 1830 professor of chemistry at Anderson's College in Glasgow and went in 1837 as professor of chemistry at the University College in London. His lectures were very popular among the students, so he had high colleges revenue. 1841 Graham wrote a textbook on chemistry, the best chemistry textbook ( "Elements of Chemistry" ) was for many decades in English. The German translation by Otto became a standard textbook for Chemistry in Germany. Already in 1836 Graham was a member of the Royal Society, from 1838 to 1841, he worked in Germany for Liebig's Annalen der Chemie and Pharmacie, 1841, he founded with other chemists, the Chemical Society of London and its first president was (Board). August Wilhelm von Hofmann, who knew Graham well, since 1845 was also a member of the British Society 1861-1863 and its Executive Board. In 1867, Hofmann on the British model, the German Chemical Society of Berlin. Graham's father became reconciled after his academic and professional success slowly with Thomas again.
In 1854 he also took over the management of the Royal Mint ( who had also passed Isaac Newton and John Herschel before him), that is, overseeing the production of money he was given. From 1854 to 1860 Graham was no longer working in scientific research.
Scientific achievements
1831 Graham published a work on salt-like compounds of alcohol and salt ( alkoxides ) and its crystal water.
1833 Graham explained the diversity of phosphoric acid and of its various kinds of salt formation on with different high hydrogen fractions. Some phosphoric acid salts in the water even gave an acid reaction. The water acts as a base, absorbs the hydrogen from the particular phosphoric acid salts. Stronger bases still took on more hydrogen. It therefore had a different number of hydrogen atoms in the acid be present.
Diffusion of gases
In 1832 he published was named after him Graham's Law, which deals with the interaction in the diffusion of gases. Dobereiner had put a slightly fractured measuring cylinder with hydrogen gas reversed in a pool of water. The liquid column rose in the measuring cylinder. The gas that leaked through the fine crack at the same pressure, had to be faster than the gas which flowed ( Effusion ). Graham now examined in a similar manner, various gases which have been separated from each other by a very thin glass tube. He found that the root of gas density ( that is, the molecular mass of the gas particles ) is inversely proportional to the velocity of the gas. This law formed the basis for the subsequent kinetic theory of gases.
Diffusion of salts in liquids
Graham now also interested in liquids and possible transmission of a saline solution into a little salty. Since he still had very little money for elaborate experiments, he took a preparation glass and filled it to the brim with a concentrated salt solution. The preparations glass was then placed in a larger glass and then he poured water into the larger glass carefully to just above the rim of the smaller vial preparations. Then he let stand the test arrangement and noted the time. Finally, it was distilled from the waters of the outer glass and certain mass. From the brine salt had diffused into the water. Depending on the nature of the materials he could find the differences in the rate of migration, so that he could also separate from each other salts ( eg, chlorides of sulfates, carbonates, potassium salts of sodium salts ).
Colloids
Based on the diffusion experiments examined Graham now the migration of solutes through a membrane. He developed the chemical dialysis. He used planiertes paper that has parchment paper by immersion in sulfuric acid or zinc chloride. The parchment paper was placed on a bell-shaped glass vessel with a central glass tube ( osmometer ). Crystalline substances could diffuse, other glue-like substances - the colloids - did not migrate through the membrane. He made this discovery in 1854, but had to write down the first discovery in 1861, enough time.
Beginning in 1866, examined Graham whether different gases can be separated by a membrane ( rubber septum ).
In his death, 1869, Graham discovered yet the connection between gaseous hydrogen with palladium metal ( "On the relation of hydrogen to palladium, and on Hydrogenium " ), he suspected that there must be a hydrogen -palladium bond.
According to him, the Thomas - Graham Prize of Colloid Society was named.