CHYMIFICATION. 589 



ceeded better. A solution, containing only 5 oi(iu P ar * f P e P s i n 

 slightly acidulated, is said to dissolve the white of an egg in six or eight 

 hours. 



Even were the evidence adduced less positive, the following pheno- 

 mena would be overwhelming in favour of the existence of some gastric 

 secretion concerned in the digestive changes in that organ. Besides 

 the fact of the most various and firm substances being reduced to chyme 

 in the stomach, we find the secretions from its lining membrane possess- 

 ing the power of coagulating albuminous fluids. It is upon the coagu- 

 lating property of these secretions, that the method of making cheese 

 is dependent. Rennet, employed for this purpose, is an infusion of the 

 digestive stomach of the calf, which, on being added to milk, converts 

 the albuminous portion into curd; and it is surprising how small a 

 quantity is necessary to produce this effect. Messrs. Fordyce 2 and 

 Young, 8 of Edinburgh, found that six or seven grains of the inner 

 coat of a calf's stomach, infused in water, afforded a liquid, which 

 coagulated more than one hundred ounces of milk, that is, more than 

 six thousand eight hundred and fifty-seven times its own weight ; and 

 yet its weight was probably but little diminished. The substance that 

 possesses this property does not appear to be very soluble in water; for 

 the inside of a calf's stomach, after having been steeped in water for 

 six hours, and well washed, still furnishes a liquor or infusion, which 

 coagulates milk. Liebig 4 has denied, that the fresh lining membrane 

 of the stomach of the calf, digested in weak chlorohydric acid, gives to 

 that fluid the power of dissolving boiled flesh or coagulated white of 

 egg; but Dr. Pereira 5 affirms, that he has found, by experiment, that a 

 digestive liquor can be prepared from the fresh undried stomach of a 

 calf. This has, indeed, been shown on the best authority long ago. 

 Mr. Hunter, for example, made numerous experiments upon the coagu- 

 lating power of the secretions of the stomach, which show, that it is 

 found in the stomachs of animals of very different classes. The lining 

 of the fourth stomach of the calf is in common use, in a dried state, 

 for the purpose mentioned above; and it has been proved, that every 

 part of the membrane possesses the same property. Mr. Hunter found, 

 by experiment, that the mucus of the fourth cavity of a slink calf, made 

 into a solution with a small quantity of water, had the power of coagu- 

 lating milk; but that found in the three first cavities possessed no such 

 power. The former, even after it had been kept several days, and was 

 beginning to be putrid, retained the property. The duodenum and 

 jejunum, with their contents, likewise coagulated milk; but the process 

 was so slow as to give rise to the suggestion, that it might have occurred 

 independently of the intestines employed for the purpose. He found, 

 that the inner membrane of the fourth cavity in the calf, when old 

 enough to be killed for veal, had the same property. Portions of the 



1 Graham's Elements of Chemistry, Amer. edit., p. 695, Philad., 1843, and Thomson's 

 Animal Chemistry, p. 229, Edinb., 1843. 



2 A Treatise on the Digestion of Food, p. 57, 2d edit, Lond., 1791. 



3 Thomson's System of Chemistry, 6th edit, iv. 596. 



4 Animal Chemistry, Webster's Amer. edit., Cambridge, 1842. 



5 Treatise on Food and Diet, Amer. edit, p. 36, New York, 1843. 



