12 Mr. Coli^iihoun on the Life and Writ tugs [Jan. 



terized by generating a great quantity of nitric acid, during the 

 progress of decomposition. In what state of combination, it 

 was vainly asked, do these three singular products, azote, am- 

 monia, and nitric acid, or their constituents, exist in the animal 

 body? It has been already remarked that BerthoUet proved azote 

 to be an invariable constituent of animal matter: he now pro- 

 ceeded a step farther by making the famous discovery that 

 ammonia is a compound of azote and hydrogen. The only 

 blank remaining to be filled up, with a view to the complete 

 development of animal nature, was the exploring of the nature 

 of nitric acid, which was successfully performed by BerthoUet's 

 friend. Cavendish, who showed it to consist of oxygen and 

 azote.* BerthoUet was now enabled to form a completely new, 

 simple, and satisfactory theory of the constitution of animal 

 substance, founded entirely on experiment, and accounting 

 easily for every appearance which had hitherto embarrassed the 

 chemist. Animal substances, said he, differ from vegetable, by 

 conlainino- a large proportion of azote as an invariable constitu- 

 ent. During destructive distillation, or during putrefaction, the 

 elements of the complex animal principles are disunited, and in 

 obedience to the new affinities which are thus called into action, 

 unite in new proportions, and form with each other more 

 simple combinations. The azote, at this time disengaged, has 

 a stronor tendency to unite with the hydrogen (another invariable 

 constituent of animal substance), the instant it is set free, and 

 the product is ammonia. In a situation favourable to the union 

 of the azote with oxygen, there will also be a formation of nitric 

 acid. 



Nothing could be more simple — nothing more complete, than 

 this explanation ; and by combining with it the brilliant disco- 

 very made shortly before by Cavendish, that water is a compound 

 of oxygen and hydrogen, a lustre was shed abroad upon the 

 science in every quarter, illuminating even those regions over 

 which obscurity had previously hung her deepest shade. In 

 almost every department of chemistry, there had till then been 

 a number of important facts unexplained, and seemingly 

 isolated, but which the intimate relations subsisting between the 

 composition of these three substances served at once to eluci- 

 date and to connect. Chemistry, at this period, was at that 

 stage of advancement, when an immense mass of facts had been 

 accumulated which, however, had no apparent dependence on 

 each other, but which only required the regard of a masterspirit 

 to be thrown over them in order at once to appreciate their indi- 

 vidual value, and their mutual relations, to penetrate the general 

 and uniform laws and principles which govern them all, and to 



■ So simultaneous were these important discoveries in the neighbouring kingdoms, 

 that the private letters of the emulous friends, mutually announcing the discovery of 

 each, are said to have actually passed each other on the way. 



