CERTAIN DERIVATIVES OF THE PROTEIDS. 319 



The ammonium sulphate-saturated fluid containing the true 

 gelatin-peptone formed by trypsin was freed from the excess 

 of ammonium salt by crystallization, the residue removed by 

 treatment with barium hydroxide and barium carbonate as 

 described in the preparation of hemipeptone, and the true 

 peptone precipitated by alcohol. After thorough and repeated 

 extraction with boiling alcohol the peptone was dried. Gela- 

 tin-peptone (L). It weighed 17 grams. The relative yield of 

 deuterogelatose and true peptone in this long-continued hy- 

 drolysis with an active solution of trypsin constitutes striking 

 evidence of the relatively slow production of true gelatin- 

 peptone in trypsin-proteolysis. 



The deuterogelatose in aqueous solution gave no precipitate 

 whatever on saturation of the fluid with sodium chloride, 

 neither did any precipitate result on addition of acetic acid 

 to the salt-saturated fluid. Consequently, it must be con- 

 sidered as entirely free from protogelatose.* Tested with 

 potassium hydroxide and plumbic acetate for loosely com- 

 bined sulphur, both peptone and gelatose gave negative re- 

 sults. Negative results were likewise obtained with Millon's 

 reagent and the xanthoproteic test. With the biuret test, 

 strong solutions of both gelatose and peptone yielded a bright 

 pink color. The composition of these two products is shown 

 by the following results. 



ANALYSIS OP DEUTEROGELATOSE (K)t. 



L 0.2811 gram substance gave 0.1705 gram HaO = 6.74 per cent H and 



0.5201 gram CO 2 = 50.46 per cent C. 



II. 0.2895 gram substance gave 0.1769 gram H 2 O = 6.79 per cent H and 

 0.5366 gram CO 2 = 50.45 per cent C. 



III. 0.3195 gram substance gave by the Kjeldahl method 0.05556 gram N = 



17.39 per cent N. 



IV. 0.2952 gram substance gave 0.05134 gram N = 17.39 per cent N. 



V. 0.6166 gram substance gave by fusion with NaOH and KNO 8 0.0126 



gram BaSO 4 = 0.33 per cent S. 

 VI. 0.3695 gram substance gave 0.0030 gram ash = 0.81 per cent. 



* See Chittenden and Solley, Journal of Physiology, 1891, xii, p. 38. 

 t Dried at 105 C. until of constant weight. 



