256 SCIENCE PROGRESS. 



works energetically at a temperature of 20° C, but only 

 when oxygen and moisture are both present ; a rise of 

 temperature above 20° C. is slowly prejudicial to it, and 

 at 60 to 63 C. it is destroyed. It may be noted that 

 it is at this temperature that the albuminoid matter coagu- 

 lates. 



Yoshida prepared oxyurushic acid from urushic acid 

 by the action of strong chromic acid. He says that so 

 prepared, it exhibits all the properties of the lacquer 

 varnish. 



The name laccase was given to the enzyme more than 

 ten years later by Bertrand (2), who made further in- 

 vestigations into the peculiar behaviour of the latex and 

 who has ascertained several additional facts about the 

 enzyme. 



In the main he confirms the earlier work of Yoshida as 

 to the constituents of the juice. The body described as 

 urushic acid he prefers to term laccol, but he has not 

 examined it minutely on account of its deleterious pro- 

 perties. 



He prepared the enzyme by treating the latex with a 

 large excess of alcohol, which precipitated a gummy sub- 

 stance, and he purified the latter by redissolving it after 

 filtration, and again throwing it down by the addition of 

 ten volumes of alcohol. It separated out in white opaque 

 flakes which yielded on hydrolysis a mixture of galactose 

 and arabinose. 



The enzyme was extracted from the gum by treatment 

 with cold water. 



In the natural juice the laccol exists in the form of an 

 emulsion, the latter being probably due to the presence of 

 the gum. 



The laccol when separated from the latex by solution in 

 alcohol and kept from the air, remains unchanged. If a 

 little water is added to the solution in alcohol, a white 

 emulsion results, which keeps for a considerable time 

 unaltered ; but if for the water a solution of laccase is 

 substituted, the resulting emulsion turns brown at once 

 and rapidly becomes black, especially if air is admitted. 



