145 
and naphthaline, and on a new acid produced. 
quantity in the heavier of the bodies above described, that 
product may conveniently be called the impure solid acid. 
The experiments made with it, and the mode of obtaining 
the pure acid from it, are now to be described. 
Upon applying heat and agitation to a mixture of one 
volume of water, and five volumes of impure solid acid, the 
water was taken up to the exclusion of nearly the whole of 
the free naphthaline present ; the latter separating in a co- 
lourless state from the red hydrated acid beneath it. As the 
temperature of the acid diminished, crystallization in tufts 
commenced here and there, and ultimately the whole became 
a brownish yellow solid. A sufficient addition of water dis- 
solved nearly the whole of this hydrated acid, a few flakes 
only of naphthaline separating. 
A portion of the impure acid in solution was evaporated 
at a moderate temperature ; when concentrated, it gradually 
assumed a light brown tint. In this state it became solid on 
cooling, of the hardness of cheese, and was very deliquescent. 
By further heat it melted, then fumed, charred, &c. and 
gave evidence of the abundant presence of carbonaceous 
matter. 
Some of the impure acid in solution was neutralized by 
potash, during which no naphthaline or other substance 
separated. The solution being concentrated until ready to 
yield a film on its surface, was set aside whilst hot to crys- 
tallize : after some hours the solution was filled with minute 
silky crystals, in tufts, which gave the whole, when stirred, 
not the appearance of mixed solid salt and liquid, but that of 
a very strong solution of soap. The agitation also caused 
the sudden solidification of so much more salt, that the whole 
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