Mr. Faraday on the mutual action of sulphuric acid, &c. 141 
Mr. Brande, several years since,* stated that naphthaline 
dissolved in heated sulphuric acid “ in considerable abund- 
ance, forming a deep violet coloured solution, which bears 
diluting with water without decomposition. The alkalies 
produce in this solution a white flaky precipitate, and if 
diluted the mixture becomes curiously opalescent, in conse- 
quence of the separation of numerous small flakes.” The 
precipitate by alkali was probably one of the salts to be 
hereafter described. 
Dr. Kidd observes, -f that “ it blackens sulphuric acid when 
boiled with it ; the addition of water to the mixture having 
no other effect than to dilute the colour, neither does any 
precipitation take place upon saturating the acid with am- 
monia.” 
Mr. Chamberlain states, J that sulphuric acid probably 
decomposes naphthaline, for that it holds but a very small 
quantity in solution. The true interpretation of these facts 
and statements will be readily deduced from the following 
experimental details. 
1 . Production and properties of the new acid formed from 
sulphuric acid and naphthaline. 
Naphthaline, which had been almost entirely freed from 
naphtha by repeated sublimation and pressure, was pulve- 
rised ; about one part with three or four parts by weight of 
cold sulphuric acid were put into a bottle, well shaken, and 
left for 36 hours. The mixture then contained a tenacious 
* Quarterly Journal of Science, viii. 289, 1819. 
f Philosophical Transactions, 1821, p. 216. 
X Annals of Philosophy, N. S. vi. p. 136, 1823. 
