SANGER-RIEGEL. — PYROSULPH. CHLORIDE-CHLORSULPH. ACID. 675 



sodic chloride and excess of sulphur trioxide until the retort contents 

 were completely melted. On rectifying the distillate over fused sodic 

 chloride, he obtained a liquid boiling at 145-150°; specific gravity, 

 1.762; vapor density, 3.76 (referred to air), which he considered from 

 the analysis to be pyrosulphuryl chloride. These properties, however, 

 together with the fact that it reacted violently with water, show a con- 

 siderable admixture of chlorsulphonic acid. This is apparently the 

 only source of the statement one finds in the literature that pyrosul- 

 phuryl chloride is formed by heating sodic chloride with sulphur 

 trioxide.'' 



Action of Non-metallic Chlorides on Sulphur Trioxide. 



Rose 8 in 1838 passed the vapor of anhydrous sulphur trioxide through 

 sulphur monochloride at low temperature. On fractioning the product, 

 an oily liquid of specific gravity 1.818 at 15° was obtained, boiling at 

 145°, which was slowly decomposed with water. This was the first prep- 

 aration of pyrosulphuryl chloride, but it undoubtedly contained chlor- 

 sulphonic acid which is invariably formed whenever sulphur trioxide is 

 chlorinated in the presence of even a small amount of water (v. Table II), 

 and there may have been some sulphur monochloride present, since the 

 boiling point of the latter, 138°, is so near that of the main product. 

 By using phosphorus trichloride Rose obtained a similar liquid, boil- 

 ing between 137° and 165°, containing much phosphorus. In 1839 

 Rose,® with the idea of preparing sulphuryl chloride, discovered in the 

 same year by Regnault,^*' mixed fused sodic chloride with "pure" 

 pyrosulphuryl chloride, probably prepared by a modification i* of his 

 original method, in which he distilled sulphur monochloride with ordi- 

 nary fuming sulphuric acid. A solid mass was formed, resembling that 

 which he had previously obtained ^ by the action of sodic chloride on 

 sulphur trioxide. Distillation gave chlorine, sulphur dioxide, and a 

 liquid boiling at 145°, which he concludes to be pure, undecomposed 

 pyrosulphuryl chloride. PYom consideration of our work, the result is 

 clear. There was much chlorsulphonic acid in the supposed "pure" 

 pyrosulphuryl chloride, and this was converted to its sodium salt, from 

 which the unchanged pyrosulphuryl chloride was distilled. If Rose 



'' E. g., Roscoe and Schorlemmer, Treatise on Chemistry, I, 438 (1905); 

 Dammer, Handbuch, I, G67 (1892). 



* Ann. d. Phys. u. Cham., 44, 291 (1838); Berzelius Jahresb., 19, 201 (1840); 

 Gmelin, Handbuch, I, 778. 

 » Pogg. Ann., 46, 167 (18.39). 

 " Compt. rend., 7, 895 (1838). 

 " Pogg. Ann., 46, 177 (1839). 



