143 
and naphthaline , and on a new acid produced. 
time the heavier substance also became solid. In this state, 
whilst in the tube, they could with great difficulty be distin- 
guished from each other. 
These two substances were separated, and being put into 
tubes, were further purified by being left in a state of repose 
at temperatures above their fusing points, so as to allow of 
separation ; and when cold, the lower part of the lighter 
substance, and the upper, as well as the lower part of the 
heavier substance, were set aside for further purification. 
The heavier substance was a red crystalline solid, soft to 
the nail like a mixture of wax and oil. Its specific gravity 
was from 1.3 to 1.4, varying in different specimens ; its taste 
sour, bitter, and somewhat metallic. When heated in a tube, 
it fused, forming as before a clear but deep red fluid. Further 
heat decomposed it, naphthaline, sulphurous acid, charcoal, 
&c. being produced. When heated in the air it burnt with 
much flame. Exposed to air it attracted moisture rapidly, 
became brown and damp upon the surface, and developed a 
coat of naphthaline. It dissolved entirely in alcohol, forming 
a brown solution. When rubbed in water a portion of naph- 
thaline separated, amounting to 27 per cent, and a brown 
acid solution was obtained. This was found by experiments 
to contain a peculiar acid mixed with a little free sulphuric 
acid, and it may conveniently be called the impure acid. 
The lighter substance was much harder than the former, 
and more distinctly crystalline. It was of a dull red colour, 
easily broken down in a mortar, the powder being nearly 
white, and adhesive like naphthaline. It was highly sapid, 
being acid, bitter, and astringent. When heated in a tube it 
melted, forming a clear red fluid, from which by a continued 
