352 Dr. Stenhouse on the Products of the [June 15, 



Mitscherlich's statement* that he has "succeeded as little as Faraday in 

 combining benzol with ordinary strong sulphuric acid," I have found it 

 advisable, when large quantities of sulphobenzolic acid are required, to 

 treat the purified benzol with ordinary commercial acid. 



Concentrated sulphuric acid and purified benzol, in the proportion of 

 about four measures of the former to five of the latter, were placed to- 

 gether in a flask furnished with a long condensing-tube, and heated on a 

 sand-bath for eight or ten hours. The flask in which the digestion is 

 performed should be very large in proportion to the quantity of benzol 

 employed, so that an extensive surface is exposed to the action of the 

 acid f. 



Sulphobenzolates. 



The crude sulphobenzolic acid obtained by either of the above methods 

 was separated from the uncombined benzol, and a quantity of water, about 

 twenty times the bulk of the sulphuric acid originally employed, was added 

 to it. This solution, which has a small quantity of sulphobenzene, 

 C ]2 II 10 SO 2 , suspended in it, was heated to the boiling-point, neutralized 

 with chalk, diluted with ten parts more water, and after being boiled for a 

 few minutes, was filtered from the sulphate of calcium. The clear and 

 slightly coloured filtrate is a solution of sulphobenzolate of calcium, 

 Ca C 6 H 5 SO 3 , from which the salt may be obtained by sufficient concentra- 

 tion. Sulphobenzolate of barium may likewise be prepared in a similar 

 manner to the calcium salt, substituting carbonate of barium for chalk. 

 The sulphobenzolates of the alkaline metals are readily obtained by pre- 

 cipitating the solution of the calcium salt by the carbonate of the desired 

 metal, and evaporating the solution. By this process purified benzol 

 yielded nearly twice its weight of sulphobenzolate of sodium. The sulpho- 

 bemolates of copper, zinc, &c., are best prepared by precipitating the 

 solution of the barium compound by solutions of their sulphate. The 

 copper salt is usually described in handbooks, on Mitscherlich's authority , 

 as forming fine large crystals. I have only been able to obtain it, whether 

 from water or spirit, in very small crystals, which are exceedingly soluble. 



Decomposition of Sulphobenzolate of Sodium. 



The sodium-salt, after being reduced to powder and thoroughly dried, was 

 introduced into a copper flask furnished with a bent tube, and submitted 

 to destructive distillation, when an oily body covered with a layer of water 

 condensed in the receiver, and a considerable quantity of carbonic and 

 Some sulphurous acid gas were evolved, carbonaceous matter and carbonate 

 of sodium remaining in the retort. In order that the operation may pro- 

 ceed rapidly, and in the most advantageous manner, the quantity of sub- 



* Pogg. xxxi. p. 284. 



t A similar process has been employed by Gerhardt and Chancel in the preparation 

 of sulphite of chlorobenzene, Compt. Kend. vol. xxxv. p. 690. 

 \ Gmelin'8 Handbook, vol. xi. p. 150 ; Gerhardt, vol. iii. p. 72. 



