496 Mixter — Formation of the Oxides of Molybdenum, etc. 



Te0 2 is accompanied by little or no heat effect. The results 

 indicate that the reaction is slightly endothermic. 



The heat effect of Na„0,S0 3 derived from Thomsen's data is 

 125'6 C and from the writer's* 123'7 C . That of Na 2 0,Te0 3 is 

 124*3 approximately. If we take 162*5 C based on Thomsen's 

 results and subtract Se,30 = 42*4 C , we have 120*l c for N a 2 0,- 

 Se0 3 . The heat of the reaction Na 2 0,R0 3 where R is sulphur, 

 selenium or tellurium, is probably nearly the same in all cases. 

 This much is however, evident, that it does not increase or 

 diminish notably with increasing atomic weights as it does in 

 the reaction Na 2 0,R 2 5 where R is phosphorus, arsenic, anti- 

 mony, and bismuth,*)- or in Na 2 0,R0 3 , where R is chromium, 

 molybdenum and tungsten. Moreover the heat effect of Na a O- 

 R0 3 is in all cases higher where R is sulphur, selenium 

 or tellurium, than where R is chromium, molybdenum or 

 tungsten. 



* This Journal, vol. xxvi, 125. f Loc. cit. 



