SANGEK-RIEGEL. — PTEOSULPH. CHLORIDE-CHLORSULPH. ACID. G99 



From Sample B, the following figures were obtained : 



3. At 20°, 14.0425 g. substance occupied the same volume as 7.6333 



g. water. S. g. 20° 1.8354 



4° 



4. At 20°, 14.0508 g. substance occupied the same volume as 7.6333 



g. water. S. g. 20^ 1.8365 



4° 



The specific gravity of Sample C (Preparation 6) after taking a melt- 

 ing point determination, was 1.8364 at 20°, referred to water at 4°. 

 It was again distilled with salt under diminished pressure. Of this 

 product, 



5. At 20°, 14.0538 g. substance occupied the same volume as 7.6333 



g. water. S. g. 20^ 1.8369 



4° 



6. At 20°, 14.0525 g. substance occupied the same volume as 7.6333 



g. water. S. g. 20^ 1.8367 



4° 



7. At 0°, 14.3292 g. substance occupied the same volume as 7.6423 



g. water. S. g. 0^ 1.8718 



4° 



8. At 0°, 14.3277 g. substance occupied the same volume as 7.6423 



g. water. S. g. 0^ 1.8716 



4° 



(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 pyrosulphuryl chloride at 20°, referred to 

 4°, is therefore 1.837 ; at 0°, referred to water at 4°, 1.872. 



Melting Point. — The determination of this constant, which plays a 

 very important part in the purification of pyrosulphuryl chloride and 

 chlorsulphonic acid and their differentiation, was made in two ways. 

 The first method, particularly available for small quantities of substance, 

 is analogous to that so commonly employed in the determination of 

 the melting point of organic substances, in which the material is placed 

 in a thin-walled " capillary " tube, closed at one end. This we shall 

 refer to as the "capillary method." In the second, which we shall call 

 the "immersion method," the thermometer is placed in a test tube 

 containing a comparatively large (Quantity of (substance, so that the en- 

 tire thread may be covered by the substance when melted. 



A Rothe ^^ thermometer filled with pentane was used, 35 cm. long, 

 graduated from 30° to —200° in whole degrees. As this was grad- 



"' Zeitschr. f. Instrumentcnkunde, 24, 5 (1904). 



