M. H, Chittenden — Ferments of Pineapple Juice. 303 



is evident from the fact that the several precipitates produced by 

 heat are more sohible in dihite alkalies than is customary for coagu- 

 lated globulin, and that the precipitate produced by addition of 

 dilute hydrochloric acid is so readily soluble on warming the neutral 

 or slightly acid mixture, followed by its re-appearance as the tem- 

 perature is lowered. On the other hand, the pronounced insolubility 

 of the proteid in warm nitric acid of all strengths is contrary to the 

 usual behavior of the proteoses. Further, the substance gives a 

 biuret reaction more violet than red, and when boiled for a short 

 time with 0*5 per cent, sodium carbonate it is transformed appar- 

 ently into alkali-albumin, since the precipitate resulting from neu- 

 tralization of the alkaline fluid is then insoluble in salt solution, 

 although readily dissolved by a slight excess of dilute hydrochloric 

 acid. 



It is further evident that the proteolytic ferment of pineapple 

 juice is either associated with this peculiar globulin or proteose-like • 

 body, or else is the body itself. The above method of precipitating 

 the proteolytic ferment, by saturation of the juice with sodium 

 chloride, brings about a complete separation of the ferment, provided 

 the fluid is fully saturated with the salt. The filtrate, however, still 

 contains some proteid matter, precipitable by shaking the fluid with 

 neutral ammonium sulphate. This substance was separated from a 

 lai'ge quantity of juice, by treating the filtrate from the sodium 

 chloride precipitate with ammonium sulphate, added to complete 

 saturation. 



The slight stringy precipitate which resulted was filtered off, 

 dissolved in water and dialyzed. After several days a small portion 

 of the solution, though still containing some salts, was tested as 

 follows : heated gradually the solution became slightly turbid at 65°- 

 70° ('., with separation of flocks at 80°-82° C. The filtrate from this 

 precipitate gave no further signs of separation even when heated to 

 boiling, but a drop of acetic acid added to tlie hot fluid })roduced a 

 slight turbidity. 



The dialysis was continued for about ten days longer, until the 

 salts were almost wholly removed, when the solution was found 

 faintl}^ alkaline and slightly turbid. This turbidity disappeared 

 at once on addition of a drop of dilute nitric acid, also on the addi- 

 tion of a few drops of salt solution. Addition of 0*2 per cent, hydro- 

 chloric acid to faint acid reaction produced a slight precipitate, 

 readily soluble in salt solution. Subjected to heat precipitation, the 

 turbid fluid cleared up somewhat at first, then became slightly turbid 



