and Casein Peptone. 93 



c. Caseoses formed hy dilute sulpJmric acid at 100° C. 



Two kilos, of pure moist casein were heated in a flask with 2 

 litres of water and 100 grams of pure sulphuric acid at 100° C. for 

 seven hours. The residue of casein and antialbumid was again 

 warmed with a like amount of fresh acid and water for six hours. 

 The acid fluids were united, neutralized with sodium carbonate with- 

 out giving any noticeable precipitate, and then evaporated until 

 moderately concentrated. On cooling, considerable tyrosin and 

 leucin crystallized from the fluid. With cupric sulphate, the solution 

 gave a heavy precipitate which dissolved in sodium hydroxide with 

 a reddish color. Sodium chloride and ammonium sulphate both pro- 

 duced heavy ])recipitates when added to saturation. 



The caseoses were separated from the fluid by saturation in the 

 cold with ammonium sulphate, and from this precipitate, protocaseose 

 was separated by solution in water and precipitation with sodium 

 chloride. The sodium chloride precipitate was dissolved in water, 

 the substance roprecipitated by saturation with salt, and again dis- 

 solved in water to which a trace of sodium carbonate was added 

 to make the mixture quite neutral. On dialysis, a small amount of 

 gummy heterocaseose separated, mixed with a little tyrosin. The 

 clear fluid, now free from salts, was concentrated on a water-bath. 

 As the evaporation advanced, a brown gummy mass settled out, 

 which was, however, readily soluble in cold water, for as the concen- 

 trated fluid cooled at night the gummy matter entirely disappeared, 

 reappearing as the fluid was again heated. The final concentrated 

 fluid was treated with alcohol, the gummy precipitate boiled with 

 alcohol repeatedly to free it from any adhering tyrosin, and finally 

 extracted with ether and dried at 110° C. 



Analyzed, it gave the following results : 



Frotocaseose, formed by sulphuric acid. 



I. 0"4405 gram substance gave 0.2*718 gram H^OrzG'SS per cent. 

 H and 0-8756 gram CO„=54"20 per cent. C. 



II. 0*;3783 gram substance gave 0'2341 gram H„0 = 6'87 per cent. 

 H and 0.7604 gram C02=ro4-81 per cent. C. 



III. 0*3786 gram substance gave 48-3 c. c. N at 17-5° C. and 753*4 

 mm pressure= 14*93 per cent. N. 



IV. 0*3780 gram substance gave 47*8 c. c. N at 17*0° C. and 754*0 

 mm pressure=:14*84 per cent. N. 



V. 0*3701 gram substance gave 0*0113 gram ash = 3*05 per cent. 



VI. 0*5112 gram substance gave 0*0154 gram ash = 3*02 per cent. 



