163 



lates two equivalents, and is converted into a bibasic acid (ethionic), 

 C 4 H 4 4SO 3 + 2HO = C 4 H ( .O 2 4SO 3 , which accordingly may be 

 viewed as an association of alcohol with four equivalents of anhy- 

 drous sulphuric acid. Terms analogous to ethionic acid are sure to 

 be found when the study of the homologues of sulphate of carbyl 

 shall be taken up by chemists. 



The production of disulpho-com pounds of perfectly similar com- 

 position, from substances belonging to such different groups of bodies, 

 as the hydrocarbons homologous and analogous to marsh-gas, ethy- 

 lene and alcohol, suggested the possibility that the substances in ques- 

 tion might be but individual examples illustrating a far more general 

 mode of formation. It became, in fact, probable that all organic 

 bodies capable of uniting with the elements of two equivalents of 

 anhydrous sulphuric acid might, under favourable circumstances, be 

 induced to assimilate two additional equivalents of anhydrous sul- 

 phuric acid, and thus furnish other terms belonging to the class of 

 disulpho-compounds. 



The only additional class of compounds to which we have as yet 

 successfully extended our labours, is the group of organic bases. 



Action of Sulphuric Acid upon Aniline. 



The first product which sulphuric acid forms with aniline is 

 simply the sulphate of the base. 



A further addition of acid, assisted by heat, dissolves the sulphate, 

 and after a sufficiently long digestion, the whole is converted into 

 sulphanilic acid. If too high a temperature be employed, the acid 

 becomes very dark in colour ; and indeed there is a limit beyond 

 which carbon is rapidly deposited, accompanied by the evolution of 

 abundance of sulphuric acid. 



The process of converting sulphanilic acid into the disulpho-com- 

 pound is rather tedious. It may, however, be effected without fail, 

 by treating for several hours the perfectly dry crystalline acid, mixed 

 with strong Nordhausen acid, to the consistence of a paste. The 

 heat should not exceed that at which sulphurous acid just com- 

 mences to be evolved. We employed an air-bath heated from 160 

 to 170 C., and the digestion was continued until a portion removed 

 by a glass rod showed no trace of crystallization when cooled or 

 moistened with water. 



