1826.] Sulpho-Naphthalic Acid. 197 



tional of the acid consists of two proportionals of sulphuric 

 acid, twenty of carbon, and eight of hydrogen ; these consti- 

 tuents forming an acid equivalent in saturating power to one 

 proportional of other acids. Hence it would seem, that half 

 the sulphuric acid present, at least when in combination, is 

 neutralized by the hydrocarbon; or, to speak in more general 

 terms, that the hydrocarbon has diminished the saturating 

 power of the sulphuric acid to one half. This very curious and 

 interesting fact in chemical affinity was, however, made known 

 to me by Mr. Hennell of Apothecaries' Hall, as occurring in 

 some other compounds of sulphuric acid and hydrocarbon, 

 before I had completed the analysis of the present acid and 

 salts ; and a similar circumstance is known with regard to mu- 

 riatic acid, in the curious compound discovered by M. Kind, 

 which it forms with oil of turpentine. Mr. Hennell is, I believe, 

 on the point of offering an account of his experiments to the 

 Royal Society, and as regards date they precede mine. 



It may be observed, that the existence of sulphuric acid in 

 the new compounds, is assumed, rather than proved ; and that 

 the non-appearance of sulphurous acid, when sulphuric acid 

 and naphthaline act on each other, is not conclusive as to the 

 non-reaction of the bodies. It is possible that part of the 

 hydrogen of the naphthaline may take oxygen from one of the 

 proportions of the sulphuric acid, leaving the hyposulphuric 

 acid of Welter and Gay-Lussac, which with the hydrocarbon 

 may constitute the new acid. I have not time at present to 

 pursue these refinements of the subject, or to repeat the ana- 

 lyses which have been made of naphthaline, and which would 

 throw light upon the question. Such a view would account for 

 a part of the overplus in weight, but not for the excess of the 

 sulphuric acid obtained, above two proportionals. 



The glowing salt of baryta was now analysed by a process 

 similar to that adopted for the flaming salt. The specimen 

 operated upon was pure, and in a distinctly crystalline state. 

 It had been heated to about 440 F. for three hours in a me- 

 tallic bath. Ten grains of this salt, exposed to air for forty 

 hours, increased only 0*08 of a grain in weight. These, when 

 converted into sulphate of baryta by heat and sulphuric acid, 

 gave 4*24 grains. Seven grains by carbonate of baryta, oxide 



