1825.] of Claude-Louis Berthollet. 11 



even at this early period he stood pre-eminent among the 

 chemists of his day, by his superior acquaintance with the 

 resources of analysis, and by his greater penetration in fore- 

 seeing the new apphcations of which they were susceptible. 

 But although this is not one of the discoveries which redounds 

 most to the fame of the individual, it is one which has contri- 

 buted most materially to the advancement of science. The 

 pure caustic alkali has continued ever since that moment a most 

 powerful instrument in the conduct of almost every department 

 of analysis, in the animal, the vegetable, or the mineral king- 

 dom ; and to it we are especially indebted for almost all the 

 knowledge we possess respecting the constitution of the pre- 

 cious stones, and other refractory mineral compounds. The 

 greatest eclat does not always attend the most useful improve- 

 ments. 



The year 1785 was on many accounts a remarkable one in the 

 life of Berthollet. In it he had the honour of being the first 

 French chemist of any note who acceded to the doctrines of 

 Lavoisier : in it he gave to the world his brilliant discovery of 

 the composition of ammonia ; and in the course of the same 

 year, he published his first essay on the Nature of Dephlogisti- 

 cated Marine Acid, or Chlorine, thus entering upon a field from 

 which he afterwards reaped so rich a harvest of fame. 



The constitution of azote and its combinations had long been 

 a bar to the progress of the Lavoisierian doctrines. Nothing 

 can be more strongly marked than the difference which exists 

 between the natures of animal and vegetable substance, yet 

 there was no subject whose investigation proved more difficult 

 for chemists, than the cause of these distinctions. One of the 

 first steps towards distinguishing these characteristics was made 

 by Berthollet, when, in 1780, he showed that a large proportion 

 of azote forms an invariable constituent in every animal sub- 

 stance. Still, however, the prominent part which azote performs 

 in chemistry organic and inorganic, long continued an impene- 

 trable mystery, and remained one of the last and most serious 

 obstacles to the establishment of Lavoisier's theory. Nor need 

 this mystery be wondered at, for at this time neither the com- 

 position of ammonia nor of nitric acid was known, and water, 

 which so often mingled itself in every analysis, was yet regarded 

 as an element. 



The destructive distillation, or the spontaneous putrefaction of 

 animal substances, gives invariably as one product a quantity of 

 the volatile alkali : the same process applied to a vegetable prin- 

 ciple, as certainly produces a substance of an acid nature. 

 Bodies belonging to eitlier class, when abandoned to spontane- 

 ous decomposition, yield matter which is eminently adapted to 

 the support of vegetable life ; but in addition to this, subjects of 

 the animal kingdom; under certain circumstances, are charac- 



