SANGER-RIEGEL. — SULPHUR TRIOXIDK-SILICON CHLORIDE. 585 



second distillation, which weighed 23 grams and boiled from 45.8° 

 to 48.2° at 11-13 mm. This material analyzed gravimetrically con- 

 tained: 



s Si Ci 



(2) 14.63% 10.20% 54.87% 



(3) 14.50% 10.18% 

 IS2O5CI0 



+ lSioOCl6 



12.82% 11.31% 56.69% 



The composition of an equi-molecular mi.xture of pyrosulphuryl chlo- 

 ride and silicon oxychloride is given above, and it can be seen that the 

 liquid gives similar figures. 



Distilled at atmospheric pressure the temperature rose steadily 

 and evenly from 141° to 150°. No crystals were obtained on cooling. 

 To the distillate one fifth of its weight of pyrosulphuryl chloride was 

 added, and it was then distilled again when the temperature readings 

 were unchanged. On cooling no crystals were formed; the material 

 congealed as before, below —100°. 



In our second extended experiment 236 grams of silicon tetrachloride 

 and 221 grams of melted anhydrous sulphur trioxide, that is, one mole- 

 cule of the former to two of the latter, were heated in the air-bath for 

 six hours at 50° and deposited 8 percent of a white solid. 205 grams 

 of the liquid poured off from this solid were distilled at ordinary pres- 

 sure and gave 



90 grams at 37-44° 



62 " " 44-58° 



31 " " 59-145° 



21 " " residue. 



(Sulphur trioxide boils at 46°, silicon tetrachloride at 57°). The third 

 fraction and the residue gave on a second distillation 20 grams at 135- 

 151° and 16 grams at 151-172°; these 20 grams did not crystallize on 

 cooling, and were therefore distilled again, and separated into four 

 fractions. The second one only, 6 grams collected at 137-145° (4, 5) 

 could be made to crystallize at —83°, melting at —50°; the remaining 

 three fractions were combined and distilled, the distillate being col- 

 lected in 3 portions, the middle one, 138-143° (8, 9) crystallized spon- 

 taneously; the lower one, 136-138° (6, 7), on stirring; the upper one, 

 143-176° (10, 11) only on seeding from the lower one. As none of 

 these fractions showed any signs of constant boiling-point, the crystal- 

 lization was studied further. For this purpose each fraction was 



