186 Hydrolysis of the Solnhle Protein of Simde Tmmips 



The ammonia was removed from the remaining 800 c.c. by evapora- 

 tion with barium carbonate and magnesia on the water bath for two 

 hours. The two portions freed from ammonia were combined, and 

 the alkahne magnesia and barium carbonate mixture filtered off and 

 thoroughly washed ; the excess of barium was removed from the filtrate 

 by dilute sulphuric acid, and the precipitate filtered ofi and washed 

 out. Filtrate and washings were combined together, evaporated down 

 and made up to 1 litre, and a Kjeldahl nitrogen determination again 

 made. Allowing for the nitrogen given off as ammonia, the diflerence 

 between this and the previous estimation gives the "Humin Nitrogen 

 II" contained in the alkaline barium carbonate magnesia mixture. 



5 c.c. gave NHg equal to 16-66 c.c. N/10 acid. 

 5 c.c. gave HNg equal to 16-70 c.c. N/10 acid. 

 Average 16-68 c.c. 



= 0-02335 grm. N. 

 1000 c.c. contain 4-670 grm. N. 

 Weight N before removal of ammonia = 5-1642 grms. 

 Weight N lost in ammonia = 0-3507 grm. 



Humin Nitrogen II must be 0-1431 grm. 



Leaving 4-6704 grms. 



Humin Nitrogen II = 2-77 per cent, of total nitrogen. 



3. Precipitation of arginine and histidine. 



This was carried out according to the method of Kossel and 

 Kutscher. The solution of the bases finally obtained was made 

 up to 1 litre; a Kjeldahl nitrogen determination in 20 c.c. gave the 

 amount of nitrogen in the silver- baryta precipitate. 



20 c.c. gave NH3 equal to 12-40 c.c. N/10 acid. 

 20 c.c. gave NH3 equal to 12-52 c.c. N/10 acid. 

 Average 12-46 c.c. 



= 0-01744 grm. N. 

 Total nitrogen in silver-baryta precipitate =- 0-8722 grm. 



4. Estimation and isolation of histidine. 



{a) The greater portion of the histidine was removed by precipita- 

 tion with mercuric sulphate. The solution was concentrated to about 

 250 c.c, and sulphuric acid added till the solution contained 5 per cent. 

 of it. The solution was treated with 10 per cent, mercuric sulphate 

 solution in 5 per cent, sulphuric acid until no further precipitate was 



