190 
Proceedings of the Royal Society 
First Preparation. 
1 Second Preparation. 
I. 
II. 
I. 
II. 
Carbon, .... 
71-55 
71-50 
71'69 
71-71 
Hydrogen, 
8'32 
8-13 
7-60 
7-72 
Oxygen, 
20-13 
20-37 
2071 
20-57 
100-00 
100-00 
100-00 
100-00 
Mean. 
Theory for C 14 H 18 0 ; 
requires 
Carbon, . 
71-61 
71-79 
Hydrogen, 
7-94 
7-69 
Oxygen, 
20-45 
20-52 
100-00 
100-00 
This substance is very stable, and resists the action of strong 
mineral acids except hot fuming nitric acid, which gradually changes 
it to a yellowish body, and finally into the new acid previously 
mentioned, C 9 H 18 (COOH) 4 . bio solvent has yet been found for it. 
The strength and durability of lacquer varnish are due to the 
presence of this oxy-urushic acid. Many experiments on the harden- 
ing of lacquer were made by Mr J. Takayama, and they con- 
clusively establish the fact that hardening is due to the oxidation of 
urushic acid, aud not to its hydration. 
Some drying oil is frequently added to the lacquer juice to make 
varnish. I have studied this point, to learn how far the introduc- 
tion of the oil is admissible, without impairing the essential quality 
of the lacquer. It is ascertained that the addition of 10 to 15 per 
cent, of the drying oil to the juice does not hinder the hardening 
power of the lacquer, and 20 or 25 per cent, of the oil can be intio- 
duced without much had effect. Such a mixture gives a varnish of 
greater transparency and spreading power than the pure juice itself, 
but its capability of withstanding strong chemical reagents is pro- 
portionally reduced. The results arrived at may he summoned up 
in the following statements : — 
1. Lacquer juice consists essentially of four substances, viz., 
urushic acid, gum, water, and nitrogenous matter. 
