90 PROF. H. E. ROSCOE ON CERTAIN 



terized compounds"*, and Debray, obtaining abnormal 

 numbers for the vapour- density of the monoxy chloride, is 

 unable to explain the cause of his results. 



The splendid, red, needle-shaped crystals of the mon- 

 oxy chloride are best obtained by passing the vapour of a 

 chloride over heated oxide, or dioxychloride, in a current 

 of chlorine. The crystals melt at 2io°'4 (corrected), and 

 solidify at 2o6°"j C. ; when heated more strongly, the 

 liquid boils at 22j°'$ (corrected), forming a red vapour, 

 rather lighter coloured than that of the hexachloride. On 

 repeated distillation over red-hot charcoal in a current of 

 chlorine the hexachloride is formed. On exposure to air 

 it becomes at once covered with a yellow crust of tungstic 

 acid, from which it is difficult to obtain it quite free. 



Analysis gave : — 



Calculated. Found. 



Tungsten, W 53'8o 5389 



Chlorine, Cl 4 A-i'S z 4111 



Oxygen, 4/68 



Debray (Compt. Rend. lx. p. 820) determined the vapour- 

 density of the monoxy chloride in sulphur-vapour to be 148 

 (H = 1), whereas the calculated density is 1 7 1 . It appeared 

 therefore of interest to repeat this determination. 



Vapour -density of WC1 4 O in Sulphur-vapour. 



I. II. 



Weight of bulb in air 21-6315 20*5745 grms. 



Barometer 754 761 mm. 



Temperature 1 1 ° 1 3 C. 



Weight of bulb and vapour, 1 . 



„ \ 22-2965 21-0780 grins, 



at 440 C J ° 



Capacity of bulb *4 2 '73 107-350.0. 



Hence vapour-density (H =1)171-3 1717 



* " Le tungstene, pas plus que le phosphore, n'engendre d'oxychlorure. 

 Les composes que Ton a ainsi designes sont des combinaisons en proportions 

 definies, mais variables, d'acide anhydre avec le chloride correspondent." — 

 Comptes Boukts, lvii. p. 766. 



