Messrs. Dalzell and Thorpe on Sulphur Dichloride. 309 



tubes to about 150°; in a few minutes combination was quickly- 

 effected, and the entire contents of the tubes were transformed 

 into colourless phosphorus sulphochloride, which boiled, con- 

 stantly at 126°-6 C. at 770 millims. barom. As thus obtained, 

 it is a colourless mobile liquid ; its vapour is extremely irritating, 

 and possesses a sharp aromatic odour, which when diluted re- 

 minds one of that of the raspberry. It is but slowly decomposed 

 by water. 



XXXV. On the Existence of Sulphur Dichloride. 

 By John Dalzell and T. E. Thokpe, Ph.D., F.R.S.E* 



WHEN dry chlorine in excess is passed through molten 

 sulphur, a dark red fuming liquid slowly distils over. 

 This, on renewed distillation, commences to boil at about 50° or 

 60°, and the thermometer slowly rises to 136° or 137°, at which 

 point it remains stationary, and the orange-yellow disulphide 

 CI 2 S 2 passes over. The fraction boiling below 136° frequently 

 amounts to three fourths of the original quantity of liquid ; on 

 again submitting it to distillation the same order of things is 

 repeated, and but a comparatively small portion distils over 

 above 136°. At each distillation the liquid becomes lighter in 

 colour, until at length, by long-continued boiling, it assumes the 

 bright yellow of the disulphide, and boils constantly at 136-137°. 

 This behaviour would seem to indicate the existence of some 

 compound of chlorine and sulphur, which slowly undergoes de- 

 composition on distillation, ultimately forming the disulphide; 

 and the observations of Dumas and Soubeiran, and of Mar- 

 chand, Davy, and Rose, point to a body richer in chlorine 

 than the disulphide; and their analyses lead to the formula 

 S CI 2 . On the other hand, Carius denies the existence of sul- 

 phur dichloride in the dark-red liquid obtained by heating 

 sulphur in chlorine, and asserts that the compound analyzed 

 by Dumas and others was a mixture in atomic proportions 

 of the disulphide with a tetrachloride of sulphur hitherto un- 

 isolated (CI 2 S 2 + SCI 4 = 3C1 2 S). According to Carius, the 

 amount of chlorine contained in the liquid, over and above that 

 required by the formula S 2 CI 2 , is altogether dependent on 

 the temperature. But the fact of the protracted distillation 

 required to break up the product into a liquid boiling con- 

 stantly at 136-137° implies that the excess of chlorine is held 

 by some other force than that of mere solution ; and at the 

 same time we are not altogether without facts more directly 

 indicating the existence of the dichloride. Rose has obtained 



* Communicated by the Authors, having been read at the Meeting of 

 the British Association at Edinburgh, September 1871- 



