298 a. H. Chittenden — Ferments of Pineapple Juice. 



not allowed to pass beyond 40" C. This is demonstrated by the 

 following experiment : 



Experiment XVI. — The pineapple juice employed had an acidity 

 equal to 0*445 per cent. HCl, 100 c. c. requiring 13 c. c. of a 5*0 per 

 cent, solution of sodium carbonate for neutralization. The 10 arrams 

 of albumin coagulum used in the digestions contained 1-3633 grams 

 of dry albumin, 



A 100 c. c. pineapple juice + 13-0 c. c. 5 i^er cent. NaaCOa sol. 



B 100 •• " +13-0 " 



C 100 ■' " +13-0 " H,0 



D 100 " " +13-0 " 



Solutions B and D were evaporated to dryness on plates at 40° C, 

 the residues dissolved in water and made up to 113 c. c. respectively. 

 All four solutions Avere then mixed with 10 grams of albumin coag- 

 ulum and warmed at 40° C. for 3^ hours, after which the amount of 

 albumin digested was determined in the usual manner. 



From these results, it is plain that pineapple juice of natural 

 acidity can be evaporated to dryness at a temperature not exceeding 

 40° C. and still preserve its proteolytic power. With neutralized 

 juice, however, the above results indicate a partial destruction of the 

 ferment during the evaporation. Whether this is due to the action 

 of the neutral salts formed by neutralization of the acid, or to some 

 other cause we cannot say. Possibly, the solution may have been 

 made slightly alkaline, which would naturally give rise to some de- 

 struction of the ferment. Several repetitions of the above experi- 

 ment, less carefully conducted, have shown that evaporation of the 

 acid juice, however, is very liable to result in a pai'tial loss of pro- 

 teolytic power, unless great care is taken in keeping the evaporating 

 fluid at 40° C. or under. 



3. — Mate of action. 



Pineapple juice is not only exceedingly active on proteid matter, 

 but under favorable circumstances the digestive power of the fer- 

 ment is quickly manifested. On blood fibrin and muscle tissue, 

 especially, the proteolytic action of the ferment is shown in a rapid 



