90 It. H. Chittenden — Caseoses, Casein Dyspeptone, 



Protocaseose agrees closely in its content of carbon with the 

 " propeptone I " of Thicrfelder.* This investigator has separated 

 from a pepsin digestion of casein, by a process similar to our method 

 of separating the proto body, a substance to which he gives the 

 above name and which contained 54'63 per cent, of carbon and 7-45 

 per cent, of hydrogen. In reactions it was similar to protocaseose, 

 except that aqueous solutions of the substance remained perfectly 

 clear on warming. Nitrogen was not determined. Thierfelder also 

 separated from the filtrate from his " propeptone I," a second body, 

 by addition of hydrochloric acid, to which he gives the name " pro- 

 peptone II." This substance, which corresponds to our a deutero- 

 caseose, he found to contain 49-8 per cent, carbon, 7"1S per cent, 

 hydrogen and 14-23 per cent, nitrogen. Judging from the method 

 of separation, however, the body analyzed must liave been an acid 

 compound of the caseose and not the caseose body itself. In reac- 

 tions, so far as they are given, the substance was not different from 

 a deuterocaseose. 



b. Caseoses from WeyVs casehi 23eptone. 



This commercial product, sent to lis from Germany, we have 

 examined according to the foregoing methods and have found it, as 

 might be expected, composed almost entirely of caseoses. It was 

 completely soluble in water and gave with acetic acid a slight tur- 

 bidity, somewhat increased by addition of potassium ferrocyanide. 

 By saturation of its aqueous solution with sodium chloride, only a 

 comparatively small precipitate was obtained, greatly increased, how- 

 ever, by addition of acetic acid. 



200 grams of the powder were dissolved in water and the caseoses 

 precipitated collectively by saturation of the fluid with ammonium 

 sulphate, in the form of a heavy gummy precipitate. On heating 

 the filtrate from this precipitate of caseoses until a crust of ammo- 

 nium sulphate formed on the surface of the hot fluid, a second 

 gummy precipitate gradually separated, which after purification by 

 dialysis, etc., was finally precipitated by alcohol, and a portion dried 

 at 110° C. for analysis. 



This substance, representing a form of caseose not readily precipi- 

 table by ammonium sulphate and thus indicating its close approach 

 to true peptone, is apparently identical with the ft deuterocaseose 

 similarly obtained in our own digestion, but present here in much 



* Zeitschrift fiir physiologische Chemie, Band x, p. 585. 



