54 
were, while those portions which were in contact with the 
sides of the bottle, which receive as much light as if 
there were not any glass sides before it, were not at all 
blackened. This phenomenon is just complementary to the 
first one, proving that the blackening in the atmosphere is 
in all probability due to the oxygen of the air, but not the 
light alone, nor the combined action of light and air. 
The lacquer when distilled with water gives a colourless 
distillate which is slightly acid to test paper, and the 
attempt has been made to examine the acid, but not 
successfully on account of too minute quantity of the sub- 
stance evolved. Distillation by itself and in a current 
of steam was tried also, but the results in both cases were 
the same as the first one. Lastly distilled with a small 
quantity of dilute sulphuric acid, to aid the substance to 
distil over, into sugar of lead, scarcely any precipitate was 
obtained. 
Lacquer mixes with any kind of fixed oil in all propor- 
tions ; hence oil is often added as adulteration, but some- 
times it is purposely added to increase its mobility. 
The specimen of lacquer which I examined consisted of 
the following three substances : 
Part soluble in absolute alcohol 
I. 
II. 
(resin) 
58*24 
58*23 
Gum 
6*34 
6*30 
Residue 
2-24 
2*30 
Moisture and other volatile matter 
33*175 
33*170 
100-00 100*00 
As I have already mentioned, the lacquer loses its weight 
very rapidly when exposed to the atmosphere. For the 
above determination I weighed out each time samples from 
well stoppered bottles, and determined the weight by 
difference. Then this was treated with absolute alcohol and 
