142 Mr. Faraday on the mutual action of sulphuric acid 



deep red fluid, and a crystalline solid ; it had no odour of 

 sulphurous acid. Water being added, all the liquid and part 

 of the solid was dissolved ; a few fragments of naphthaline 

 were left, but the greater part was retained in solution. The 

 diluted fluid being filtered was of a light brown tint, trans- 

 parent, and of an acid and bitter taste. 

 ^^ For the purpose of combining as much naphthaline as 

 possible with the sulphuric acid, 700 grains, with 520 grains 

 of oil of vitriol were warmed in a Florence flask until 

 entirely fluid, and were well shaken for about 30 minutes. 

 The mixture was red ; and the flask being covered up and 

 left to cool, was found after some hours to contain, at the 

 bottom, a little brownish fluid, strongly acid, the rest of the 

 contents having solidified into a highly crystalline mass. 

 The cake was removed, and its lower surface having been 

 cleaned, it was put into another Florence flask with 300 grains 

 more of naphthaline, the whole melted and well shaken toge- 

 ther, by which a uniform mixture was obtained ; but opaque 

 and dingy in colour. It was now poured into glass tubes, in 

 which it could be retained and examined without contact of 

 air. In these the substance was observed to divide into two 

 portions, which could easily be distinguished from each other, 

 whilst both were retained in the fluid state. The heavier 

 portion was in the largest quantity ; it was of a deep red 

 colour, opaque in tubes half an inch in diameter, but in small 

 tubes could be seen through by a candle, or sun light, and 

 appeared perfectly clear. The upper portion was also of a 

 deep red colour, but clear, and far more transparent than the 

 lower : the line of separation very defined. On cooling the 

 tubes, the lighter substance first sofidified, and after some 



