496 Chemical Notices : — M. Persoz on Tungsten Compounds. 



presents over the other form the advantage that it is included as 

 a particular case under the equation ax 3 + bij* + cu 3 + dip + ew 3 =z0 

 (where x + y-\-u-\-v + w = 0) employed by Dr. Salmon as the 

 canonical form of equation for the general cubic surface. 



5 Downing Terrace, Cambridge, 

 April 29, 1864. 



LXXV. Chemical Notices from Foreign Journals. 



%E. Atkinson, Ph.D., F.C.S. 



[Continued from p. 115.] 



THE following are the results at which Persoz has arrived 

 after an investigation of tungsten*. 



Prom the constitution and properties of its oxygen compounds, 

 tungsten belongs to the group of biatomic elements arsenic, anti- 

 mony, and phosphorus. 



Its equivalent (0 = 8), as deduced from numerous experiments, 

 is 153-3 =W. 



It forms two oxidized, compounds; tun gstic oxide, WO 3 , and 

 tungstic acid, WO 5 . 



By their combination these two compounds can form a third 

 oxide (of the nature ofBerzeliusandDumas'ss#/me oxides), which 

 corresponds to the formula W0 3 + W0 5 = 2W0 4 . 



Tungstic acid is polybasic; its simple and double salts are 

 represented by the general formulae WO 5 , MO, HO + nAq, and 

 WO 5 , MO MO+nAq. 



Like its congeners, phosphoric and antimonic acids, tungstic 

 acid may become artificially modified by heat, so that its capacity 

 of saturation is reduced to one-half; it may be said then to give 

 rise to a [new acid, metatungstic acid, the existence of which 

 depends on definite conditions. Its formula is (WO 5 ) 2 or 

 W 2 10 . 



The simple metatungstates are represented by the formula 

 (WO 3 ) 2 MO, HO + Aq. They readily form double salts by com- 

 bining either with each other, 



[a) (WO 5 ) 2 MO, HO \ 

 (WO 5 ) 2 MO, MO J 



or with the simple tungstates, 



+ Aq, 



(b) (WO 5 ) 2 MO, HO I , 

 WO 5 MO, HO I +Aq * 



The paratungstates and certain acid tungstates come under these 

 formulae. 



Sulphur, chlorine, and bromine combine with tungsten to 

 * Comptes Rendus, November 9, 1863, 



