SANGER-RIEGEL. — SULPHUR TRIOXIDE-SILICON CHLORIDE 591 



210°, the pressure being 20 mm. throiigliout. Tlie analyses resulted 

 as follows: 



S Si CI 



(22) <) grams 19.9% 6.75% 43.4% 



(23) 4.5 grams 24.2 3.9 35.2 

 For comparison, SAClo 29.82 — 32.98 



The figures for the 9 grams indicate that no appreciable amount of 

 chlorsulphonic acid had been remove<l, hence that the water treatment 

 destroyed the silicon body, and yielded the sidphur containing body. 

 That this sulphur body is pyrosulphuryl chloride is indicated by the 

 figures for the 4.5 grams obtained by heating the salt residue to a 

 temperature excee<ling 200°, while the pressure was kept at 20 mm. 



In another preparation in which hydrous sidphur trioxide was used 

 of such a strength that there was enough water present to form 

 chlorsulphonic acid instead of pyrosulphuryl chloride according to 

 the reaction: 2SO3 f HoO + SiCb = 2CIS63H + SiOCla, that acid 

 was indeed obtained, but the reaction had taken place in a different 

 way. The water decomposed a portion of the silicon tetrachloride, 

 forming silica to such an extent that the solid residue in the flask after 

 distillation was 50 percent by weight of the materials taken, and 

 hydrochloric acid, which combined with the sulphur trioxide to form 

 chlorsulphonic acid, a portion of the silicon tetrachloride was recovered 

 unchanged in the liqui^l air condenser; all the silicon not accounted for 

 by it was present in the solid residue. 



Three preparations have been observed which approached pyrosul- 

 phuryl chloride. The most nearly pure was obtained early in our work 

 by distilling a homogeneous mixture of 115 grams of 94 percent sul- 

 phur trioxide and 111 grams of silicon tetrachloride (2 molecules to 1) 

 resulting after 12 hours' shaking at room temperature. A large 

 amount of gelatinous silica was filtered ofl" through glass wool, and the 

 144 grams of filtrate submitte<i to a distillation at low pressure; the 

 distillate was collected in four fractions; the analysis of the first one, 

 boiling at 60° to 100° with a pressure of 70 mm., has been given under 

 (20) in the table of analyses; the last, boiled at 105°, Avith the oil-bath 

 surroimding the flask 240°, and pressure 60 mm., accompanied by 

 violent foaming, and left a solid residue of 50 grams; its analysis 



follows: 



s Si ci 



Found 28% 0.17% 29.4% 



S2O5CI2 29.82 — 32.98 



The experiment on the action of water on the average distillate 



diluted by chloroform has been recorded; there too on heating to 210° 



