Biography of Berzelius. 15 



however, which he made for the purpose of determining the 

 atomic weights of the metal and earth, are probably not quite 

 decisive, and it is perhaps more likely that the earth is com- 

 posed of two atoms of metal and three atoms of oxygen. 



The next subject to which Berzelius turned his attention 

 belongs to organic chemistry. It was a comparative investi- 

 gation of tartaric and racemic acids. He first corrected his 

 former analysis of tartaric acid, in which he had given an 

 atom more hydrogen than Prout and Hermann, and adopted 

 the results of these chemists. But he then found that the crys- 

 tallised tartaric acid had precisely the same composition as 

 the effloresced racemic acid, and that both acids had the same 

 capacity of saturation, — facts which, especially at that time, 

 were in the highest degree remarkable. This was one of the 

 first clearly demonstrated examples that bodies of different 

 characters may have the same composition. Berzelius had, 

 sometime before, observed a somewhat similar fact in re- 

 ference to the oxides of tin, and Faraday, a short time after- 

 wards, in reference to the compounds of carbon and hydro- 

 gen. Clarke had also discovered the remarkable modifica- 

 tion of phosphoric acid, which he called pyrophosphoric acid. 

 On this occasion Berzelius combined together, in an interest- 

 ing manner, what was known of these bodies, to which he 

 gave the name Isomeric. This term has been universally 

 adopted, now that the number of such bodies has been so 

 greatly increased. 



From this time Berzelius frequently occupied himself with 

 subjects which are certainly of the greatest interest for every 

 thinking chemist, and indeed for every scientific man, since 

 they are calculated to unfold to us somewhat more fully the 

 nature of matter. He made known his views on this subject 

 repeatedly, both in his " Jahresberichte," and in the several 

 editions of his " Lehrbuch." Finally, he assumed two essen- 

 tially distinct kinds of isomerism, and, in the strictest sense 

 of the word, called those bodies only isomeric in which the 

 elementary atoms may be regarded as grouped in different 

 ways, forming compound bodies. These isomeric bodies may 

 again be of two different kinds. They consist either of com- 

 pounds which, with equal atomic weights, present different 



