14 
madder. Dr. Smith had found a similar colour from gas 
liquor, and Mr. Me. Dougall had found a large quantity of 
the lime compound when operating with carbolic acid. Dr. 
Smith shewed that in a purified state it formed a dark 
coloured resin unlike Runge’s substance, and that it was 
formed in various ways with great ease by the oxidation of 
carbolic acid, and that it was a product of oxidation of that 
acid with the formula C12 He O3 or C24 Hi2 Og. It formed 
picric acid by the action of nitric acid. It did not, however, 
form such compounds with the bases as Runge’s acid, the 
colour of the compounds being destroyed as soon as the 
excess of base was removed ; and in most cases the acid was 
easily separated from the base by means of ammonia. 
The carbonic acid of the air readily destroyed the bright 
colour of the salts, and reproduced the dark brown colour of 
the acid itself. The colour, therefore, could neither be trans- 
ferred to mordants nor to fabrics. For the same reason it 
could not serve as a pigment. In all probability, however, 
it was the same substance as found by Runge, although pro- 
bably from not knowing how to prepare it in sufficient 
quantities he had not. observed these facts. Although in- 
teresting, therefore, from a scientific point of view, any hope 
long entertained of applying the acid on the proposed plan 
in the arts was destroyed. 
