302 JR. H. Chittenden — Ferments of Pineapple Juice. 



On cautiously adding 0-2 per cent, hydrochloric acid to the faintly 

 alkaline fluid a heavy turbidity made its appearance, which changed 

 to a flocculent precipitate as the fluid became slightly acid ; on 

 addition of a small excess of acid the precipitate quickly dissolved. 

 From this it may be inferred that if the solution had been perfectly 

 neutral, a more pronounced sepai-ation of the proteid might have oc- 

 curred in the dialyzer tube ; evidently, however, the body is ex- 

 tremely soluble in veiy dilute acid and alkaline solutions, as well as 

 in dilute solutions of neutral salts. Thus, the precipitate produced 

 in this manner by the addition of a little 0*2 per cent, hydrochloric 

 acid was readily dissolved by 10 per cent, salt-solution, the fluid 

 becoming turbid again on boiling, with separation of a flocculent 

 precipitate. 



Further, by gently warming the turbid mixture resulting from the 

 addition of a few drops of 0-2 per cent, hydrochloric acid, the fluid 

 cleared up almostly completely, the turbidity returning as the mix- 

 ture cooled. 



Addition of dilute hydrochloric acid, however, did not precipitate 

 all of the proteid ; the filtrate still contained some proteid matter 

 and, moreover, showed marked proteolytic action on fibrin. Thus 

 in one instance, 0'2 per cent, hydrochloric acid was added to the 

 dialyzed solution until a distinct flocky precipitate resulted, this was 

 filtered off and dissolved in lu-per cent, solution of sodium chloride. 

 This solution on being heated gradually, grew turbid at GG^-GS" C. 

 but did not yield any further precipitate even on boiling. The tur- 

 bidity did not disappear on the addition of 0-5 per cent, sodium car- 

 bonate, or of 0'2 per cent, hydrochloric acid, but was soluble in dilute 

 potassium hydroxide. 



The filtrate from the above precipitate showed marked proteolytic 

 action ; it also yielded a slight precipitate with strong nitric acid, 

 not dissolved by warming; subjected to heat precipitation the solu- 

 tion grew turbid at 73° C, but did not give any further precipitate 

 even on boiling. The turbidity did not readily disappear on the 

 addition of either dilute hydrochloric acid or of 0-5 per cent, sodium 

 carbonate, but was quickly soluble in very dilute potassium hydrox- 

 ide. Evidently, the substance precipitated by the acid and that 

 remaining in solution were essentially the same. 



From the foregoing, it is plain that the proteid substance pre- 

 cipitated by saturation of neutral pineapple juice with sodium chlo- 

 ride, is a peculiar body partaking both of the characters of a globulin 

 and of heterojjroteose. That it approximates more closely to the latter 



