224 HISTORY OF CHEMISTRY. [LECTURE XII. 



in vacuo over sulphuric acid, correspond to the old formula of 

 Serullas, 9 C 4 H S + 2 SO 3 + MO + H 2 O [C=i2, 8 = 32, O = i6]. 

 Liebig confirmed this, 10 and was thereby led to pronounce 

 ethyl sulphuric acid isomeric with isethionic acid. 11 He found 

 very essential differences, however, in the behaviour of the two 

 acids towards potassium hydroxide. Whilst the former acid 

 was converted, on simply boiling with this reagent, into alcohol 

 and potassium sulphate, the latter acid was only decomposed 

 on fusion with it and gave rise to the formation of a sulphate 

 and a sulphite. This reaction induced Liebig to assume the 

 existence of dithionic acid in isethionic acid. Berzelius, who 

 adopted Liebig's view, employed it in arranging into two classes, 

 the substances produced by the action of sulphuric acid upon 

 organic compounds. 12 



Kolbe, in 1844, tried to bring into harmony with the 

 opinion of Berzelius, 13 the ingenious views of Mitscherlich 14 

 in accordance with which (following the analogy of the ordinary 

 acids) the sulpho-derivatives of the first class were regarded as 

 compounds of sulphuric acid, and those of the second class as 

 compounds of carbonic acid. He was at that time engaged 

 upon an examination of.the substance discovered by Berzelius 

 and Marcet 15 in acting with chlorine upon carbon bisulphide. 

 He fixes its formula as CC1 2 SO 2 [C = 6, O = 8, S = i6] and 

 calls it sulphite of perchloride of carbon. By treatment with 

 potash he converts this substance into Chlorkohlenunterschwefel- 

 sdure (trichlormethyl-sulphonic acid), which, in turn, is con- 

 verted by means of the reactions of Melsens 16 (that is, by the 

 action of nascent hydrogen) into Chlorformylunterschwefelsaure 

 (dichlormethyl-sulphonic acid), Chlorelaylunterschwefelsciure 

 (chlormethyl-sulphonic acid), and Methylunterschwefelsdure 

 (methyl-sulphonic acid). Kolbe regards these compounds 



9 Ann. Chim. [2] 39, 153 ; 42, 222 ; Fogg. Ann. 15, 20. 10 Annalen. 

 13, 28. u Compare p. 131. 12 Annalen. 28, I. 13 Ibid. 54, 145. 

 14 Ibid. 9, 39; Pogg. Ann. 31, 283 ; compare also Mitscherlich, Lehrbuch, 

 Third Edition, i, 107 and 586. 15 Gilb. Ann. 48, 161. 1G Compare 

 p. 171. 



