THE DECOMPOSITION PRODUCTS OF PROTEIDS. 65 



more easily obtained by treating with three parts of barium 

 hydrate at 120 C. for six to eight hours ; (iii.) a third 1 per 

 cent, is given off by treating with two parts barium hydrate 

 for twelve hours at 1 50 , and (iv.) a fourth 1 per cent, is 

 obtained by heating with excess of barium hydrate for 

 several hours at 260 . 



He next found that accompanying these four stages of 

 the decomposition there were different cleavage products 

 obtained. First, there were some insoluble barium salts, 

 viz., carbonate, oxalate, phosphate and sulphate. On calcu- 

 lating the quantities of the carbonate and oxalate formed, he 

 arrived at the interesting result, that they were present in 

 just those proportions to confirm the hypothesis, that, with 

 the ammonia set free, they had existed in the proteid mole- 

 cule as a urea, and oxamide radicle. The barium carbonate 

 and oxalate, moreover, were formed at different stages of 

 the elimination of ammonia, and by combining the results 

 obtained, he was led to the view, that the first amount of 

 ammonia came from one of the amide radicles of the 

 oxamide, the second corresponded especially to the urea, 

 and the third to the remaining nitrogen of the oxamide 

 (present then as oxamic acid). 



After precipitating the barium with carbonic anhydride 

 and sulphuric acid, he obtained, by distillation in a partial 

 vacuum, a small quantity of acetic acid mixed with traces of 

 formic acid, and an essential volatile oil which he identified 

 as pyrrol contaminated with smaller quantities of methyl- 

 and ethyl-pyrrol. 



The remaining bodies did not volatilise nor sublime at low 

 temperatures, and these he termed the " residu fixe". By 

 contrasting the elementary analysis of this with that of the 

 original albumin, and taking into account the quantities of 

 the above-mentioned substances, he was enabled to prove 

 that the essential action of the barium hydrate was one of 

 hydrolysis. 



For the qualitative analysis of the "residu fixe" he relied 

 entirely upon processes of isolation by repeated crystallisa- 

 tions from water, alcohol, or ether, after he had spent much 

 time in endeavours to effect the same object by precipita- 



5 



