SANGER-KIEGEL. — PYROSULPH. CHLORIDE-CHLORSULPH. ACID. 715 



The question was studied by us in several ways : a. Pyrosulphuryl 

 chloride was dissolved in chloroform and one molecule of water added, 

 drop by drop. Hydrochloric acid was given otf and a liquid separated 

 which was shown to be sulphuric acid. The chloroform solution was 

 then distilled to expel the solvent. The residue hissed with water, 

 left some oily drops and solidified from —30° to —100°. It was then dis- 

 solved in chloroform, and a second molecule of water added as before. 

 Hydrochloric acid was again given off, and sulphuric acid separated. 

 The residue from the chloroform evaporation hissed more violently with 

 water than before, and solidified at —95-100°. A similar treatment 

 •with a third molecule of water gave hydrochloric acid in clouds, more 

 sulphuric acid separated, and the chloroform solution yielded a small 

 residue, which still gave the reactions of chlorsulphonic acid and solid- 

 ified below —80°. The reaction was followed quantitatively, though 

 roughly, and the amount of sulphuric acid was somewhat below that 

 demanded by equation (2). 



Evidently in this experiment the reaction has taken place in two 

 stages, represented by equations (3) and (1), the net result being ac- 

 cording to equation (2), though the last action was not entirely 

 complete. 



b. Pyrosulphuryl chloride was dissolved in carbon tetrachloride, 

 and water was added directly in the proportion of 8.4 to 100 (equa- 

 tion (3)). The mixture was allowed to stand over night. From a por- 

 tion the solvent was evaporated by a rapid current of dry air ; the 

 turbid residue reacted quietly with water. The remainder was evap- 

 orated at a gentle heat, and left a residue which also gave no violent 

 action with water. This would seem to show that reaction (3) had 

 not taken place exclusively, but probably reaction (2) incompletely, 

 though, of course, at least 18 per cent of chlorsulphonic acid may have 

 been present according to Table HI, 5. 



c. Pyrosulphuryl chloride was exposed to the moist air of the room 

 in a beaker covered with a watch glass for seven days, and a portion 

 tested each day with water. There was no evidence of chlorsulphonic 

 acid, — merely a diminishing quantity of pyrosulphuryl chloride, until, 

 on the last day, the residue was sulphuric acid alone. The beaker 

 walls were covered with aqueous hydrochloric acid. 



d. 8.3 parts of water were added to 100 parts of p)TOsulphuryl 

 chloride, cooled to 0°, and shaken under ice cooling for an hour. The 

 liquid became turbid at first, and a little gas containing chlorine was 

 evolved. In twenty minutes the mixture was decidedly yellow. At 

 the end, two layers were formed, the lower, from its action with water, 

 being apparently unaltered pyrosulphuryl chloride and the upper sul- 



