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GUM AND ENZYME. 



After extracting the lac with alcohol the residue was extract- 

 ed with cold water and the gum-enzyme precipitated by pouring 

 into strong alcohol. The precipitate was dissolved in a small 

 quantity of water and reprecipitated with alcohol. By repeating 

 the operation several times and finally washing with ether and 

 drying in an exsiccator, it was obtained perfectly white and easily 

 reduced to powder. In physical appearance it is similar to pow- 

 dered acacia. When so prepared the gum-enzyme is very active, 

 rapidly changing tincture of guaiac to a deep blue color. If 

 an emulsion is made with the gum-enzyme, water and the sepa- 

 rated resin, it soon changes from yellowish-white to black. A 

 solution of gum-enzyme with naphtol formed a purplish blue 

 color, and with guiacol a red color in half an hour but produced 

 no effect upon a solution of vanillin in hydrochloric acid. If a 

 solution of the gum-enzyme is boiled with water, it becomes en- 

 tirely inactive. 



TESTS FOR NITROGEN. 



It is a generally conceded fact that all enzymes contain nitro- 

 gen. The Lassaigne test for the detection of nitrogen is un- 

 doubtedly considered the most reliable. It consists in heating the 

 substance with metallic potassium or sodium and converting the 

 cyanide so formed into Prussian blue. This test was applied to 

 the gum-enzyme, but failed to detect the presence of nitrogen. 

 According to Kehrer the Lassaigne test must be modified for 

 certain pyrrol derivatives, 78 and cannot be applied to diazocom- 

 pounds. 79 In view of the certainty of the presence of nitrogen 

 and the general reputation of the test, it was repeatedly tried with 

 various modifications. The gum-enzyme was previously mixed 

 with dry sodium carbonate and carefully ignited. The rapidity 

 of the heating was varied. In another experiment the sub- 

 stance was placed in a narrow tube closed at one .end, and the 

 tube drawn out to contract the opening, small pieces of sodium 

 were then introduced and the tube again contracted, thus : 



c 



GUM-ENZYME SODIUM 



78 Berichte, 35, 2,525 ; 1902. 



79 Berichte, 17, 1,178; 1884. 



