and naphthaline y and on a new acid produced, 145 



quantity in the heavier of the bodies above described, that 

 product may conveniently be called the impure solid acid. 

 The experiments made v^^ith 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 v^ater, and five volumes of impure solid acid, the 

 v^^ater 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 sohd. 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 



MDCCCXXVI. U 



