Headden — Tungstous Oxide, new Oxide of Tungsten. 281 



tude of their triangular bases but not always so, as the prisms 

 are sometimes very short. The triangular base is apparently 

 equilateral and I interpret the form as a hemiprism belonging 

 to the hexagonal system ; the color is gray to tin-white and 

 the luster is brilliant metallic. These crystals are sometimes 

 grouped in clusters and then the larger ones are often invested 

 with an abundance of smaller ones. Cases of penetration are 

 frequent but no surfaces other than those indicated have been 

 observed. Some of the crystals are striated, which is probably 

 due to interference. 



The magnetic portion of this second bottom, as used for 

 analysis, consisted for the most part of crystalline particles. 

 It oxidized slowly and imperfectly when fused with potassic 

 hydric sulphate, but when heated to dull redness in an open 

 crucible it ignited and burned to a voluminous powder, yellow 

 while hot but nearly white when cold. Complete oxidation 

 is effected with some difficulty. The results of the analysis 

 No. I were : 



14 



14 1 



100-20 



This suggests a mixture of 10CbO+4WO + Fe 9 Sn. Such a 

 mixture would require 24/42 per cent of its weight of oxygen 

 to completely oxidize it ; the amount absorbed upon ignition 

 was 24*88 per cent of its weight.* 



The non-magnetic portion, analysis No. II, gave 



* In separating tungstic and stannic oxides from colurnbic acid by digesting 

 with amnionic sulphide and adding hydric chloride or sulphate to the alkaline solu- 

 tion, I have frequently obtained a yellow filtrate in which a further addition of 

 hydric sulphate produced no precipitate. This reaction is due to the presence of 

 potassic oxy-sulpho-tungstate KoW0 2 S 2 which is formed by the action of the 

 amnionic sulphid on potassic tungstate formed during the fusion. The extent to 

 which this salt may be formed is shown by the fact that in one instance I ob- 

 tained rather more than one-third of all the tungstic acid present in this yellow 

 filtrate from the mixed sulphide precipitate. 



This salt is given in Gmelin-Kraut's Handbuch der Chemie, vol. ii, Part II, 

 page 126, as being sometimes met with in tho preparation of tungstic sulphide 

 by fusing together potassic tungstate and sulphur — Berzelius ; the same state- 

 ment is given in Watt's Dictionary of Chemistry, vol. v, p. 914. But the reac- 

 tion is not recorded anywhere, so far as I can find, as produced in the manner 

 here given. 







At. eq. 





Cb 



37-72 



40-13 



10 



W 



29-04 



15-80 



4 



Fe 



19-62 



35-10 



9 



Sn 



5-04 



4-27 



1 







8-78 



54-90 



14 



