SANGER-RIEGEL. — SULPHUR TRIOXIDE-SILICON CHLORIDE. 581 



yield of 5.5 grams of the oxycliloride SioOCle was obtained, after several 

 fractionations. The greater part of the crude material was silicon 

 tetrachloride, besides some 35 grams of the higher oxychlorides. The 

 method was nevertheless better than that of Friedel and Ladenburg ^°, 

 from which we obtained absolutely no yield. These five grams were 

 found to crystallize readily, melting at —41° to —38°, corr. by the 

 beaker method. ^^ 



Analyses: Rapid analyses for chlorine and sulphur were made vol- 

 umetrically. A small bulb containing a known weight was broken in 

 water; the solution made up to a definite volume and aliquot portions 

 used. As a rule part of the silica precipitate<l. The total acidity 

 was found by titrating against standard potassium hydroxide. The 

 effect of the silicic acid on the indicator (phenol phthalein) was not 

 to be considered, as the method was intended merely for following 

 changes in whole percentages. The chlorine was determined by the 

 Volhard method, with which the silver silicate does not interfere, for 

 it is readily decomposed by all strong acids. ^^ The acidity and the 

 chlorine content were expressed in terms of a normal solution ; from 

 the difference the percentage of sulphur was calculated. 

 The accurate determinations were made as follows: 

 Silicon and Sulphur: A bulb containing a known weight was broken 

 in a freshly prepared solution of sodium hydroxide made from sodium, 

 and which had been shown to contain no silica, chlorine, or sulphur. 

 The solution was filtered from the pieces of glass into a platinum dish, 

 and acidified with sulphate-free liydrochloric acid.-^^ The analysis 



10 Lieb. Ann., 147, 355 (1868) ; C. R. (1868) 66, 539; also Troost and Haute- 

 feuillc, C. R. (1871) 73. 503; J. prakt. Chcm., (2) 4, 30\ (1871). 



11 A rapid method for obtaining melting-points at low temperatures was 

 used. A small melting-point tube, as used in organic work, contains the sub- 

 stance alreadj^ crystallized by dipping it in liquid air; this is placed in a 

 beaker containing naphtha which has been cooled by innnersion in liquid air 

 also. By removing the latter, the bath is permitted to warm up until the sub- 

 stance melts; the temperature is read on a pentane thermometer calibrated 

 in the same way as it is used. A full description will be found in a previous 

 article, Proc. Am. Acad., 47, p. 699. It will be called the "beaker" method. 



In addition to this method the "immersion" method, in which the thermo- 

 meter is placed in the melting substance, after having been standardized for 

 that use, was employed whenever possible. 



12 J. D. Hawkins, Am. Jour. Sc, 139, 311 (1890). 



13 The time during which the alkaline .solution was in contact with glass 

 varied between twelve and twenty-five minutes. In order to show that no 

 glass was dissolved, the pieces of glass from one of the bulbs were collected, 

 after the alkaline solution had been removed, and weighed: 



Glass recovered 0.7458 gram. 

 " taken 0.74.52 gram. 



