and Casein Peptone. 85 



Amnwniiun sulphate precipitate. 



On adding ammonium sulphate in substance to the above salt- 

 saturated acetic acid fluid, a slight gummy precipitate was obtained, 

 readily and completely soluble in water, and which, after removal of 

 the salts by dialysis and concentration of the fluid, was precipitated 

 by alcohol. In reactions it did not differ materially from the body 

 obtained by precipitation with acetic acid, except that with cupric 

 sulphate only a slight precipitate was produced. With acetic acid 

 and potassium ferrocyanide, on the other hand, a distinct precipitate 

 Avas obtained, while with nitric acid in the cold no turbidity whatever 

 was produced. 



In composition, however, it differed decidedly from the preceding 

 preparations, although as it contained considerable ash, nearly 10 per 

 cent., the result perhaps can be considered only as an approximation 

 to the truth. 



Following is the percentage composition of the ash-free substance : 



Average. 



48-23 



6-94. 



15-63 15-75 15-69 



This body, which by analogy should be nearly pure deutero- 

 caseose, evidently approaches much nearer to our conception of a 

 true casein peptone than any of the preceding preparations. Another 

 body, however, has been obtained with a still lower content of 

 carbon and with reactions still more closely approximating to true 

 peptone. 



In the first precipitation of the caseoses fi-om this digestion by 

 saturation of the original fluid with ammonium sulphate, it will be 

 remembered that a small amount of a second gummy precipitate was 

 obtained on heating the cold saturated ammonium sulphate filtrate. 

 This gummy precipitate of a caseose body, after purification by 

 dialysis and precipitation with alcohol, was found to consist of a 

 substance extremely soluble in water, the solution giving no precipi- 

 tate with acetic acid and potassium ferrocyanide, neither with nitric 

 acid nor with cupric sulphate. After being dried at 110° C. it gave 

 on analysis the following results : 



I. 0*7280 gram substance gave 0-4239 gram 11.^0=0-46 per cent. 

 H and 1*2160 grams 00^ = 45 -54 per cent. C. 



II. 0*5020 gram substance gave 0-2905 gram 1120 = 6*40 per cent. 

 H and 0*8442 gram C0„ = 45'85 per cent. C. 



