102 B. H. Chittenden — Caseoses, Casein Dyspeptone, 



phate a heavy precipitate; and on saturation with ammoninm sul- 

 phate in the cold an abundant gummy precipitate, the latter plainly 

 indicating the presence of caseose. As the product originally 

 gave no precipitate with ammonium sulphate, it would apparently 

 follow that the peptone hy long drying at 110° C. had been, in 

 part, reconverted into caseose, and as the solution gave no turbid- 

 ity by heat it would imply that the caseose formed by the recon- 

 version of the peptone was the deutero body. Results similar to 

 these were obtained by Kiihne and Chittenden with fibrin peptone. 



In a second digestion of trypsin, 1 kilo, of moist casein was 

 warmed at 40° C. with 4 litres of 0*6 per cent, sodium carbonate 

 solution containing trypsin, well thymolized, for one week. On 

 the third day, the gelatinous coagulum already described made its 

 appearance, but gradually disappeared and at the end of the week 

 there was only a very small residue remaining. The neutralized and 

 concentrated digestive fluid, freed from more or less tyrosin by cool- 

 ing and crystallization, was in this case treated with rock salt to sat- 

 uration, yielding, however, only a small precipitate of proto- and 

 heterocaseose, which on purification agreed in reactions with the 

 caseoses previously described. Addition of salt-saturated acetic 

 acid to the sodium chloride filtrate from the foregoing caseoses, failed 

 to give any precipitate whatever, and as the saturation of the fluid 

 with ammonium sulphate gave only a slight gummy precipitate it is 

 evident that in this digestion the casein was almost completely con- 

 verted into peptone. In order to be quite sure of the complete re- 

 moval of everything precipitable by the ammonium salt the mixture 

 was boiled for some time with an excess of ammonium sulphate, and 

 the filtrate treated as described under peptone A for the complete 

 removal of tyrosin and ammonium sulphate. 



The final product was exceedingly gummy and parted with the 

 last traces of adhering alcohol very slowly. In fact, we found it best 

 to dissolve the final alcoholic precipitate of peptone in a little water, 

 and to drive ofi" the alcohol from the solution by heat, after which the 

 fluid was evaporated and the gummy peptone finally transformed 

 into a friable mass by drying on a water-bath, and at last completely 

 dried at 110° C. After its final precipitation with alcohol, an aque- 

 ous solution of the peptone gave no precipitate whatever, with nitric 

 or acetic acid, neither with acetic acid and potassium ferrocyanide 

 nor with cupric sulphate, or at the most nothing more than a faint 

 turbidity. After being dried at 110° C. until of constant weight, 

 the product then gave a decided gummy precipitate by saturation 



