338 DR A. CRUM BROWN ON THE CLASSIFICATION OF 



reactions correspond to those of the monatomic olefines the formulae of Wuetz's, 

 dihydriodate and dihydrate will be, — 



®@®®©® ®0[®® 



®-©-®-©-©-©-©-® and @ _©_ ( i > ' 

 ® ® @® ® @ X ^ 



-©-©- 

 i i 



ft) fa 



-©-©-® 

 i i 



® ® 



the latter will thus contain the radical (CH 3 e)' twice, and be a diatomic olefine- 

 hydrate. 



The organic acids derived from sulphuric acid, and which are formed by the 

 addition of S0 3 to organic substances containing hydrogen, stand in the same rela- 

 tion to sulphuric acid as the carbon acids (carbonsauren) do to carbonic acid ; in 

 these we have an organic radical replacing one HO in S0 2 (HO) 2 . They there- 

 fore contain the radical S0 2 (HO) ; which, assuming the hexatomic character of 

 the sulphur atom in sulphuric acid, may be represented by the graphic formula, 



fsj As we have numerous generic radicals derived from {(CO) HO}' 



®-®^ ' 



such as COH, CH 2 (HO), we might expect to find similar derived radicals 

 from S0 2 (HO), and there can be little doubt that substances containing such 

 radicals exist ; but as yet very few of them are known. Thus we have only 

 one or two substances corresponding to the acetones, such as sulpho-benzid, 

 (C 6 H 5 ) 2 S0 2 ; a few chlorides containing S0 2 C1, but no bodies corresponding to 

 the aldehydes or alcohols.f The remarkable substance discovered by V. Oefele, 

 and named by him " Trisethyl sulphin oxydhydrat," and which has the formula 

 S i7 (C 2 H 5 ) 3 (HO), is a proof of the possibility of such bodies. This substance has 

 the same relation to sulphurous acid that Butleeow's trimethyl alcohol has to 

 carbonic acid. 



As the radical COHO unites with itself to form oxalic acid, so we have 



®hr® 

 S0 2 HO, forming hyposulphuric acid (S0 2 HO) 2 fsj 



®-®^ ^" 



®^r® 



( - 



0-0. 



The examples of generic radicals might be considerably increased in number, 

 but as the purpose of this paper is not so much to tabulate known substances, 

 as to show how this may be done, those given above may suffice. It will be 

 seen that by this method, bodies having strongly marked chemical reactions in 

 common are placed together. The relations between different genera are 



* As this radical occurs very frequently, it may be advantageous to have a single symbol for 

 it, and I have been in the habit of using the Greek letter 2 for this purpose. Thus we have CH 3 S, 

 acetic acid ; CH 3 2 methylsulphuric acid ; CH 2 S2 sulphacetic acid, &c. 



f See Kolbk, Lehrbuch der Organischen Chemie, Bd. ii. s. 742. 



