A CONTRIBUTION TO THE KNOWLEDGE OF ARGININ. 5 



I have tried also to see whether the splitting of organic 

 bases is performed by a very dilute acid instead of a strong 

 one. For this purpose 0.5% hydrochloric acid ( 1.25C.C. cone. HC1 

 to 100 c.c. H 2 0) was mixed with powdered proteids and boiled 

 for 96 hours. But as I found still some peptone remaining unde- 

 composed, the boiling was continued for 50 hours more until no 

 trace of peptone was present. 



c). 10.27 g. crude proteids (0.822 g N) boiled with 0.5^0 

 hydrochloric acid for 146 hours (with addition of \% SnCL). 



Total dissolved nitrogen. 0.7888 100.0 



Nitrogen in copper hydrate 



precipitate. 0.014S 5.6 



Nitrogen directly precipitated by 



phospho-tungstic acid. (1) 0.2698 34.2 



Nitrogen in phospho-tungstic 



precipitate in the filtrate of 



copper hydrate. 0.2272 28.8 



Nitrogen in ammonia. 0.1033 I 3- 1 



Nitrogen in organic bases. 0.1239 15.7 



Thus by boiling with 0.$% hydrochloric acid we obtain 

 nearly the same result as with 20°^ hydrochloric acid. 



was present in the copper hydrate precipitate. But I afterwards satisfied myself that 



there are neither proteids nor peptone present ; so it must be something else. 



Phospho-tungstic acid precipitates both -ammonia and organic bases ; so we must 



subtract the nitrogen in ammonia from the nitrogen in phospho-tungstic precipitate and 



the difference is to be considered to belong to the organic bases. 



Ammonia in the hydrochloric acid extract was distilled off by magnesia in the 

 usual way. 



For the determination of nitrogen in phospho-tungstic acid precipitate, the pre- 

 cipitate was collected on a filter, washed with 5°^ sulphuric acid, dried and subjected 

 to Kjeldahl's method. 



(1) It is absolutely necessary to prove the absence of peptone in this case, because 

 it is precipitated by phospho-tungstic acid and would thus give a higher percentage of 

 nitrogen. For this purpose the original hydrochloric acid extract was mixed with an 

 excess of strong caustic soda and a few drops of very dilute solution of copper sulphate 

 was added ; but no violet colouration was observed. Further the phospho-tungstic 

 precipitate was decomposed with caustic baryta, the excess of baryta removed by 

 carbonic acid, filtered and evaporated and filtered once more. The concentrated filtrate 

 gave no biuret reaction. Therefore peptone must have been entirely ab=ent. 



