494 Mixter — Formation of the Oxides of Molybdenum^ etc. 



its dioxide do not burn well with sodium peroxide and sulphur 

 was added to supply the heat requisite for combustion. Tel- 

 lurium dioxide was obtained by heating the nitrate and fusing 

 the residue. Telluric acid was prepared by Staudemaier's* 

 method by oxidizing the dioxide with chromium trioxide. 

 The telluric acid was slowly heated in an electric furnace to 

 375-400° and until a sample did not yield water on melting. 

 The per cent of trioxide was calculated from the loss of 

 oxygen on heating a weighed portion until the weight was 

 constant. It was considered better to correct for tellurium 

 dioxide present than to attempt to remove it by hydrochloric 

 acid. Two different preparations of tellurium trioxide were 

 used. That for Experiment 5 contained 80*8 per cent of 

 trioxide, and for 6, 91*3 per cent. The following are the 

 experiments : 



1 2 



Tellurium _ 5*000 grams 6*000 grams 



Sulphur _ __. 1-000 " 1*000 " 



Sodium peroxide 20- " 30- " 



Water equivalent of system . . 3,866- " 4,032- " 



Temperature interval 2-883° 3-096° 



Heat effect 11,146° 12,483 c 



" " of sulphur.. — 5,271 c — 5,271° 



" " " iron — 48 c — 48 c 



" " " oxygen absorbed — 34 c — 34 c 



5,793° 7,130° 



For 1 gram of tellurium l,159 c l,188 c 



The result for 127*5 grams of tellurium is 149,700. 



3 4 



Tellurium dioxide 10*000 grams 10*000 grams 



Sulphur ... 1-000 " 1*000 



Sodium peroxide . _ 21- " 21* 



Water equivalent of system.. 3*906* " 3*896 " 



Temperature interval 2*968° 2'978° 



Heat effect ll,593 c ll,602 c 



" " of oxygen evolved + 51° + 1 1 C 



" " sulphur -5,27l c -5,271° 



" <• c 'iron —48° —48° 



a 



6,325° 6,393° 



For 1 gram of tellurium dioxide 633° 639° 



* Zeitschr. anorgan. Chem., x, 189. 



