13 



The residue insoluble in water was dried at 100 C. and 

 weighed. 



The water and volatile matter were determined by difference. 



Yoshida 10 used Ishii-natsu's method for the separation of the 

 constituents, but reported the part soluble in alcohol as urushic 

 acid, and that soluble in hot water as gum, identical with acacia, 

 and that which was insoluble in water or alcohol as diastatic 

 matter. 



He proved that the hardening of the lac was due to the action 

 of an oxidizing enzyme, acting in the presence of moisture. He 

 states that the enzyme is an albuminous body, coagulated by 

 boiling. In this he is mistaken for the enzyme is intimately asso- 

 ciated with the gum and cannot be separated from it, even though 

 it is destroyed by boiling. See under Gum, p. 45. 



Later Korshelt and Yoshida 11 examined several samples of 

 lac, using the same method of separation. For comparison the 

 results of these chemists are given in following tabulated form: 



It is claimed that the small quantity of oil reported is not a 

 natural constituent, but is due to the oil of Perilla that is used 

 on the knife and spatula to prevent the lac adhering to the iron. 



Yoshida states that the Yoshino sample which he analyzed 

 was collected under official inspection for chemical investigation 

 and was evidently pure and that the sample analyzed by Ishimat- 



10 Chemistry of Lacquer, Ki-Urushi. Hikorokuro Yoshida, Jour. 

 Chem. Soc. 1883, p. 472. 



11 Trans. As. Soc. Japan, 12, pp. 182 to 220. 



