1895.] PUBLIC DOCUMENT — Xo. 33. 303 



2. Artificial Digestion of Different Leathers. 



The artificial digestion of the substances above described 

 was carried out according to Stutzer's method. In the first 

 series of trials both the pepsin and pancreas solutious were 

 used. The preparation of the pepsin solution has already 

 been described. 



The pancreas solution was prepared by taking the fresh 

 pancreas of an ox, cutting it fine, mixing it with sand and 

 allowing it to stand twenty-four to thirty-six hours exposed 

 to the air. It was then rubbed with lime water and glycerine 

 (to every 1,000 grams of the pancreas-sand mixture use 3 

 litres of lime water and 1 litre of glycerine of 1.23 specific 

 gravity), and the resulting fluid allowed to stand with occa- 

 sional stirring for five days. It was then filtered through 

 cloth to remove the coarse portions, heated to 40° C. for 

 two hours, and finally filtered through folded filters and pre- 

 served in bottles. To prepare the pancreas solution used in 

 the process of digestion, 250 cubic centimeters of the above- 

 described solution were mixed with 750 cubic centimeters of 

 soda solution. The soda solution contained 5 grams of car- 

 bonate of soda dissolved in 750 cubic centimeters of water. 

 The pancreas solution thus prepared was heated for one to 

 two hours at 37°-40'° C, filtered to remove any flocky pre- 

 cipitate, and 100 cubic centimeters used for each test. 



The results of the pepsin-pancreas digestion were as 

 follows : — 



Per Cent, of Nitro- 

 gen digested. 



I. Sole-leather finely ground, 80.98 



II. Same leather after being heated six hours at 110° 



C. in pressure bottles with water, . . .97.23 

 in. Coiirse leather (free from fat), .... 52.00 



IV. PhiladeljDhia tankage, 90.64 



'Y. Dried blood, 99.13 



The above results are all very high, but this is not sur- 

 prising, for the action of dilute alkalies on leather is well 

 known and has been several times referred to. In the pres- 

 ent case, after the various leathers had been submitted to 

 the pepsin digestion there appeared to be no very great 

 change either in their appearance or bulk. Blood, on the 



