47 



and all were tested by heating with potassium hydroxide and 

 testing the vapor for alkalinity and by the pyrrol reaction. The 

 enzyme's activity is indicated by the time required from the addi- 

 tion of the tincture of guaiac to the first appearance of color and 

 afterwards to time required to produce a given shade. In each 

 case o.i gramme of the gum was dissolved in 4 cc. of water and 

 three drops of tincture of guaiac added. 



Nos. 8, 9, ii and 12 did not become as dark as standard, 

 even after standing twenty-four hours. Heat was used in the 

 manufacture of No. 13, which would have destroyed the enzyme 

 had it been present. 



As the acids prepared from active gums did not give the en- 

 zyme reaction, it is evident that the hydrochloric acid used in 

 their preparation destroyed the enzyme, but did not remove the 

 nitrogen. 



The enzyme in a solution of the gum from Japanese lac was 

 rapidly destroyed by boiling, but the powder, after heating for 

 two hours at 100 C., was still more active than any of the other 

 gums examined. The color with tincture of guaiac appeared at 

 once and in five minutes became dark blue. Another sample, 

 when heated for two hours at 120 C., required ten minutes to 

 produce the same deep blue shade. A third sample, heated for 

 two hours at 140 C., required ten minutes to produce any color, 

 but became dark blue in thirty minutes. A fourth sample, after 

 heating for two hours at 160 C., was inactive. 



