M. Dumas's Researches in Organic Chemistry. 211 



therefore the greatest satisfaction in being the channel of this award 

 of the Council of the Royal Society. 

 Mr. Daniell, 



I have to request that you will take charge of this Copley Medal, 

 and transmit it to M. Jean Baptiste Dumas, for his late valuable re- 

 searches in Organic Chemistry, and more especially those contained 

 in a series of memoirs on chemical types and the doctrine of substi- 

 tution*, and also for his elaborate investigations of the atomic weights 

 of carbon, oxygen, hydrogen, nitrogen, and other elements. In be- 

 stowing this Medal, as awarded by the Council of the Royal Society 

 for scientific labours so important, I may well feel the highest grati- 

 fication \. 



Having now performed this, the most agreeable duty of a Presi- 



[* See Phil. Mag. S. 3. vol. xvi. p. 322.] 



f After the classification of organic substances under compound radicals, 

 no feature in the recent progress of chemistry is more remarkable than the 

 vast additions of new compounds produced by the application of artificial 

 agencies to existing organic products. To this progress M. Dumas has 

 greatly contributed by fixing attention on the removal of one element by 

 another, which occurs in these reactions, and in particular to the equiva- 

 lent substitution of chlorine for hydrogen, which has been successfully 

 executed in a variety of substances by M. Dumas himself, and by others 

 whom his discoveries and speculations have drawn into this fruitful field 

 of research. The preservation of certain fundamental properties in the 

 new compounds thus produced, he has referred to the existence of a pecu- 

 liar arrangement of the constituent atoms in a compound, which arrange- 

 ment is supposed to be preserved on the removal of one atom, or success- 

 ive removal of several atoms, and their replacement by an equal number 

 of atoms of a different element, and is expressed by the " chemical type." 



In M. Dumas's first memoir on Chemical Types, his views are illustrated 

 by the discovery of chloro-acetic acid, a remarkable substance, and highly 

 interesting in its composition, being an acetic acid (vinegar), of which the 

 whole hydrogen has disappeared, but is replaced by an equivalent quantity 

 of chlorine. In this paper, also, he first forms " marsh gas " by an arti- 

 ficial process, and shows its relation to the acetates. He also forms a series 

 of compounds by the action of chlorine upon marsh gas or " the gas of the 

 acetates." 



The second memoir of the series makes known the action of hydrated 

 potass upon the alcohols, and furnishes a new and simple method of pro- 

 curing the acid equivalent to a given alcohol*. Thus acetic acid is alcohol, 

 in which two atoms of hydrogen are replaced by two atoms of oxygen, and 

 that acid is shown to be produced by the action of hydrate of potass upon 

 alcohol at a high temperature, with the evolution of hydrogen gas. To 

 estimate the value of these discoveries, it is necessary to bear in mind the 

 importance lately acquired by the bodies of which common alcohol is the 

 type. To discover or characterize a body as an alcohol, is to enrich organic 

 chemistry with a series of products analogous to those which are presented 

 in mineral chemistry by the discovery of a new metal. M. Dumas then 

 applies this new method to other alcohols, and obtains by it formic acid 

 from wood- spirit, ethalic acid from the ethal of spermaceti, and valerianic 

 acid from the oil of potatoes. 



In the third memoir, M. Dumas, in conjunction with E. Peligot, de- 



[• See Phil. Mag. S. 3. vol. xviii. p. 203.] 

 P2 



