94 PROF. H. E. ROSCOE ON CERTAIN 



evolved ; and when the vaponr of the same acid is passed 

 over the heated body, the formation of an ammonium salt 

 was observed as in the case of the dichloride. 



Analysis No. I. was made from a portion of substance 

 which was partially oxidized, Nos. II. and III. from a 

 purer preparation. 



Analyses of Tungsten Dibromide, WBr 2 . 



I. II. III. 



Weight of substance taken 0*6354 1*1874 0-8040 



„ tungsten obtained ... 0-3261 0-6149 



„ tungsten trioxide ... 0-5374 



,, silver bromide 0-6287 !'3 112 



„ silver 0-0260 o*oo68 



Percentage of tungsten 5 r 3 2 5 l 'l% 53' 01 



„ bromine 45- 12 47*41 



Calculated. Mean. 



Tungsten, W =184 53*49 5 2 *°3 



Bromine, Br 2 =i6o 46*51 46*26 



344 ioo-oo 98-29 



OxYBROMIDES OF TUNGSTEN. 



i. Tungsten Monoocy bromide, WBr 4 0. — This substance 

 is formed, together with the dioxybromide, by acting on a 

 heated mixture of equal parts of metal and tungsten di- 

 oxide bv bromine. It forms in brownish-black, crystalline, 

 shining needles, which are easily fusible, and can be sepa- 

 rated from the dioxybromide by gentle sublimation, when 

 the latter compound remains behind. The monoxybromide 

 melts at 277 , and boils at 32 7°* 5 (corrected), and is readily 

 acted on by water. 



The preparation used for Analyses I. and II. contained 

 a small quantity of dioxybromide. 





I. 



II. 



III. 



IV. 



Weight of substance taken . . 



. 0-9980 



1-1985 



I'22l8 



17388 



„ tungsten found . . 



• 0*3665 



0-4419 







., tungsten trioxide . . 







0-5624 





„ silver bromide 





1-6683 





2-5041 



silver 





0-0163 





0-0130 



