SANGER-EIEGEL. — PYROSULPH. CHLORIDE-CHLORSULPH. ACID, C97 



pyrosulphuryl chloride results, and the yield of chlorsulphonic acid is 

 rapidly diminished by the increasing proportion of water. The eco- 

 nomic preparation of pyrosulphuryl chloride demands an oleum contain- 

 ing at least 95 per cent of sulphur trioxide and a large excess of carbon 

 tetrachloride. 



The purification of the products of some of these preparations is 

 given in the following. 



Purification of Pyrosulphuryl Chloride and Determination of 



Constants. 



Boiling Point. — 106 g. of crude substance from Preparation 5 

 were twice distilled over salt, and 70 g. were obtained boiling at 55-57° 

 (18 mm.), with melting point of —38-35° (corr.). 

 This product was then distilled into a 3 -way ' ^ 



Bredt ^^ receiver, the arms of which carried (i) a 

 small distilling flask, (2) a Y-tube in which 

 samples could be sealed off for analysis, melting 

 point, and vapor density, and (3) a flask adapted 

 to the arm of the pyknometer in which the spe- 

 cific gravity was to be determined. The entire 

 distillate came over at 56-57° (19 mm.) Sam- 

 ple A. 



15 g. of the above were distilled from an oil 

 bath in the flask in which they were collected. 

 The thread of the corrected thermometer was 

 entirely in the vapor. A U-tube ^® in liquid air 

 connected with the receiver. Distillation 



was 



began at 142°, the thermometer rose rapidly, and 

 all came over mainly at 152-153° (766.6 mm., Figure 1. 



corr.). The U-tube contained some barely visible 

 white specks, melting at room temperature with odor of sulphur diox- 

 ide. 50 g. of the original distillate, some of which had been open to 

 the air, were also distilled. While the boiling point was again chiefly 

 from 152° to 153°, it was not perfectly constant, and there was more 



^'^ Anschlitz, d. Destination unter vermindertem Druck, 1895. 



"^ Tiiese U-tubes, the construction of which is clear from Figure 1, are 

 readily made from pieces of wide and narrow tubing to fit the Dewar liquid 

 air container. The position of the side-tube prevents its being clogged by 

 solids. By rapid work weighings can be made within half a gram; condensed 

 gases are evaporated at room temperature, hquids may be poured off, and a 

 residual solid weighed in its turn. Very satisfactory approximations may 

 be made in this way. 



