104 R. IT. Chittenden — Caseoses, Casein Dyspeptone, 



III. 0-5432 gram substance gave 68-0 c. c. N at 14-6° C. and 

 756-4 mm pressure= 14-88 per cent. N. 



IV. 0-6280 gram substance gave 0*0449 gram ash = 7-15 per cent. 



V. 0*4060 gram substance gave 0-0288 gram ash = 7 -09 per cent. 



Percentage composition of ash-free substance. 



Average. 

 49-52 



6-60 



15-99 15-99 



This peptone, like the preceding, after being dried at 110° C, gave 

 a small gummy precipitate on saturation of its solution with ammonium 

 sulphate, and also gave a precipitate with nitric and acetic acid, and 

 a slight turbidity with cupric sulphate. 



In composition, all three of the peptones show a smaller 

 percentage of carbon than the caseoses formed by trypsin, but 

 somewhat to our surprise the percentage of carbon is higher 

 than in some of the caseoses formed by pepsin-hydrochloric acid. 

 The nature of the substance, however, which at present affords 

 but little proof that we have to deal with a single body, the 

 extreme difficulty of obtaining it in a condition of dryness suit- 

 able for analysis, and the almost utter impossibility of freeing 

 it from adhering inorganic salts, all tend to throw doubt on the 

 analytical data as expressing the composition of pure casein pep- 

 tone. As already stated, there is unquestionably more or less of a 

 decomposition or change attending the drying of the peptone. So 

 pronounced is the hygroscopic character of these bodies, that when 

 partially dried they will gain weight over strong sulphuric acid, and on 

 being taken from the air bath Avhile drying at 110° C. we often no- 

 ticed on damp days a hissing noise as if from the rapid absorption of 

 water. Further, as the drying progressed the odor of valerianic acid 

 became quite pronounced and on testing the dried product, it was 

 often found to have an acid reaction so pronounced in many cases as 

 to give a sour taste to the peptone, in addition to the characteristic 

 bitter. Before drying, the peptones were usually found to have a 

 neutral reaction. These facts coupled with the changed behavior of 

 the product towards ammonium sulphate, point to a change in the 

 nature of the peptone, which may well be assumed to affect its com- 

 position, and hence we would have our analytical figures taken with 

 some allowance. 



