SANGER-RIEGEL. — PYROSULPH. CHLORIDE-CHLORSULPH. ACID. 711 



The 261 g. of Preparation 15, which melted at —79°, corr., were in- 

 troduced into the separator in several portions, and cooled until nearly 

 solid. Crystallization was spontaneous or induced by slight stirring. 

 The crystals were then allowed to half melt, and the residual liquid was 

 drawn out. The remelted crystals, united, were put into the separator 

 a second time and the crystallization repeated. The second crop of 

 crystals was then used for determination of constants. 



Melting Point. — Three determinations of melting point by the im- 

 mersion method (page 699) gave— 81°, —81°, and— 81.5°, an average of 

 —81.2°, which, corrected, becomes —80.2°. Taking this into consideration 

 with the result of the fractional crystallization of Preparation 17, we 

 may place the melting point of chlorsulphonic acid at —81° to —80°, corr. 

 The purity of the twice crystallized product of Preparation 15 is shown 

 by the slight change in melting point following the treatment. 



Specific Gravity. 



1. At 20°, 13.4138 g. substance occupied the same volume as 7.6333 



20° 

 g. water. S. g. .^ 1.7533 



2. At 20°, 13.4145 g. substance occupied the same volume as 7.6333 



20° 

 g. water. S. g. ^ 1.7536 



3. At 0°, 13.6420 g. substance occupied the same volume as 7.6423 



g. water. S. g. ^ 1.7839 



4. At 0°, 13.6410 g. substance occupied the same volume as 7.6423 



0° 

 g. water. S. g. j^- 1.7838 



(The data above are corrected in order to give the figures for specific gravity: 

 weights of water to 4°, all weights to vacuum.) 



The specific gravity of chlorsulphonic acid at 20°, referred to water 

 at 4°, is therefore 1.753 ; at 0°, referred to water at 4°, 1.784. 



Boiling Point. — The boiling point of this sample was compared with 

 that of other preparations. About 60 g. were distilled at 765 mm., corr., 

 with thread of thermometer in the vapor. Ten per cent of the distillate 

 came over at 144-151°, with traces of hydrochloric acid and chlorine. 

 The remainder boiled between 151° and 152°, with no evidence of decom- 

 position in the liquid air tube, which was placed after the receiver. 

 There was a slight residue of sulphuric acid. 



Vapor Deyisity. — The determinations of vapor density were made by 

 the method of Victor Meyer at the temperature of boiling aniline (184°). 

 The same precautions were taken as in the case of pyrosulphurjd 

 chloride. 



