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 solidified, and after some 
