716 PROCEEDINGS OF THE AMERICAN ACADEMY. 



phuric acid. The amount of unaltered substance was greater than if 

 only one molecule of water had been added according to equation (2). 



e. 8.1 parts of water were added to 100 parts of pyrosulphuryl 

 chloride warmed to blood heat. Hydrochloric acid was given off, and 

 the mixture separated into two layers, sulphuric acid and apparently 

 unchanged pyrosulphuryl chloride, colored by chlorine. The amount 

 unaltered was again greater than would have been expected if some- 

 what less than one molecule of water (8.1 parts) had acted according 

 to equation (2). 



From Experiments h, c, d, and e it might be concluded that pyrosul- 

 phuryl chloride was directly converted by water to hydrochloric and 

 sulphuric acids, except for the fact that a considerable admixture of 

 chlorsulphonic acid might show no violent action with water (Table 

 III), and that, in Experiments d and e, the amount of unaltered pyro- 

 sulphuryl chloride is greater than it should be if only one third had 

 been converted to hydrochloric and sulphuric acids. Experiment a, 

 however, shows that there is an intermediate stage of conversion, — to 

 chlorsulphonic acid. In general, a greater concentration of water will 

 bring about a more complete decomposition of the pyrosulphuryl 

 chloride, after the admixed chlorsulphonic acid has been disposed of, 

 and, in addition, the reaction is furthered by a high temperature or 

 long contact, or by both. If the reaction mixture is at once distilled, 

 the first product, chlorsulphonic acid, may be isolated. This is shown 

 by our investigation of the Prandtl and Borinski method of separation, 

 in which distillations of moist " pyrosulphuryl chloride " obtained by 

 this method gave invariably large amounts of chlorsulphonic acid. 

 One instance will suffice : 



/. 133 grams of moist "p)TOSulphuryl chloride," which had no longer 

 given any evolution of hydrochloric acid on adding ice, thus, showing 

 the chlorsulphonic acid in the original mixture to have been decom- 

 posed, were distilled. Up to 148°, 75 g. were obtained ; from 148° to 

 153°, 40 g. Both fractions reacted violently with water and gave a 

 strong red color with tellurium. 



We are now in a position to explain why the results of Konovalofif 

 and of Billitz and Heumann differed from those of Prandtl and Bo- 

 rinski. The first three authors apparently distilled their mixture of 

 pyrosulphuryl chloride and water within a short time, and therefore 

 obtained more chlorsulphonic acid, since at the higher temperature the 

 pyrosulphuryl chloride was hydrated more quickly and there was 

 not enough water left to entirely decompose the chlorsulphonic acid 

 formed. The last two, however, distinctly state that the cooled mix- 

 ture stood over night before separation and distillation, hence, at the 



