902' Mr. Faraday on the Mutual Action of Sulphurk Acid [^EPt. 



kar action exerted on certain of those compounds by sulphuric 

 acid. During my attempts to ascertain more minutely the 

 general nature of this action, I was led to suspect the occasional 

 combination of the hydro-carbonaceous matter with the acid, 

 and even its entrance into the constitution of the salts, which 

 the acid afterwards formed with bases. Although this opinion 

 proved incorrect, relative to the peculiar hydro-carbons forming 

 the subject of tliat paper, yet it led to experiments upon analo- 

 gous bodies, and amongst others, upon naphthahne, which termi- 

 nated in the production of the new acid body and salts now to 

 be described. 



Some of the results obtained by the use of the oil-gas-products 

 are very peculiar. If, when completed, I find them sufficiently 

 interesting, I shall think it my duty to place them before the 

 Royal Society, as explicatory of that action of sulphuric acid 

 which was briefly noticed in my last paper. 



Most authors who have had occasion to describe naphthaline, 

 have noticed its habitudes with sulphuric acid. Mr. Brande, 

 several years since,* stated that naphthaline dissolved in heated 

 sulphuric acid " in considerable abundance, 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 consequence of the separation of numerous small 

 flakes." The precipitate by alkali was probably one of the salts 

 to be hereafter described. 



Dr. Kidd observes,t 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 precipi- 

 tation take place upon saturating the acid with ammonia.*' 



Mr. Chamberlain states,{ that sulphuric acid probably decom- 

 poses 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 Sul- 

 phuric Acid and Naphthaline, 



Naphthaline, which had been almost entirely freed from 

 naphtha by repeated sublimation and pressure, was pulverized ; 

 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 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 



• Quarterly Journal of Science, viii. p. 289, 1819. 

 t Philosophical Transactions, 1821, p. 216. 

 . $ Annals of FbUosophif, N. S. vi. p. 136^ lfi23. 



