IMIDES OF BENZENEDISULPHONIC ACIDS. 11 



The double salt of silver and j)oiassium. 



0.1943 gr. gave, on boiling with dilute hydrochloric acid, 0.0463 gr. 



silver chloride. 

 0.2127 gr. gave 0.0496 gi-. f>ilver chloride. 



fl7.949é 

 Silver found < 



\l7.56 „ 



f SO, . C«H, . S0..1 

 Calculated for AgN I ' i NK 18.52,, 



III. p-Benzenedisulphoxime and the Imide. 



These Compounds can be prepared from p-benzenedisulpho- 

 cliloride in the same maimer as that already described for the 

 meta-isomer, pure p-benzenedisulphochloride being obtained as a 

 by-product in the preparation of beuzenetrisulphochloride accord- 

 ing to the method of Jacksox and Wixg (Amer. Ch. Journ., g, 

 332 ; 1889). The disulphochloride obtained in this way seems to 

 be the purest ever prepared, there being no need of purifying 

 it from the meta- and ortho-isomers. The disulphochloride was 

 repeatedly crystallised from ether, until its melting jwint was 

 found to be 140.5°. 



p-Benzenedisulphoxime . 



The reduction of p-benzenedisulphochloride by zinc dust 

 took place as easily as in the case of the meta-compouud, and 

 gave the sparingly soluble zinc salt of the corresponding sulphinic 

 acid. This was converted into an alkaline salt, and treated with 

 sodium nitrite and dilute sulphuric acid. The oxime of p- 

 benzenedisul phonic acid was obtained as a very fine white pre- 



