588 PROCEEDINGS OF THE AMERICAN ACADEMY. 



the analyses not already given the product for (19) was made by 

 heating solid sulphur trioxide and silicon tetrachloride in sealed 

 tubes at 250°; when the tubes were opened there was no pressure, 

 showing that no gas was formed by the reaction. A fraction boiling 

 at 135-157° was purified by distilling it at a pressure of 1.5 mm., and a 

 product obtained boiling at that pressure at 29.5° to 34°. A prepara- 

 tion made almost like that of analysis (2) and (3) yielded a lower 

 fraction analyzed under (20) while a higher fraction which approached 

 pyrosulphuryl chloride in composition and behavior will be discussed 

 later. Finally three analyses were made of fractions obtained from a 

 liquid similar to the preceding ones, but which had been treated with 

 water, in order to destroy if possible one of the constituents; one of 

 these fractions (21) was submitted to two distillations at low pressure; 

 another (22) was this preceding product after treatment with salt, , 

 in order to remove any chlorsulphonic acid which might have been 

 formed by the action of the water; the third (23) was collected from 

 the same flask, but after the temperature had been raised from 150° 

 to 210°, with the pressure still 20 mm., a degree of superheating almost 

 certain to cause decomposition, since the average boiling-point at such 

 pressures is below 100°. This action of the study of water will be re- 

 ferred to further on. , 



The percentages of chlorine marked "calculated" in the table were 

 obtained by computing the percentage of chlorine which would cor- 

 respond to the percentage of silicon in each analysis if this were pres- 

 ent as silicon oxychloride, Si20Cl6. The amount of chlorine was then 

 calculated which would be combined with the percentage of sulphur 

 if this was present as S2O5CI2, and subtracted from the percentage 

 of chlorine recorded by the analysis and the remainder entered as 

 "Found" in the table. 



From this table it would appear that 13 out of the 18 analyses agree 

 within 2 percent, of the calculated amount of chlorine in a mixture of 

 pyrosulphuryl chloride and silicon oxychloride, and one more (18) 

 within 2^ percent; moreover, among these 14, 8 agree within 1 percent. 

 Of the four which do not agree, all were analyses of fractions boiling 

 at higher temperatures than the average, 135-150°; thus (10) and (12) 

 at 143-174°, (22) at 52-110° with a pressure of 20 mm. and (23) over 

 110° with the same pressure, the oil-bath around the boiling flask being 

 finally at 210°. These high temperatures indicate that impurities 

 were present, hs products of decomposition, or substances due to the 

 action of moisture from the air and of organic matter in the shape of 

 unavoidable rubber stoppers; there would seem to be sufficient ground 



