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



Heat effect.. 10,472° 8,619 c 15,173° 



" of oxygen set free +796° +362 c -f- 39 c 



" " oxidation of carbon.. —6,876° — 6,075° 



" " " " sulphur. —10,542° 



" " " " iron —48° —48° —48° 



4,344° 2,858° 4,622° 



For 1 gram of Mo0 3 579° 559° 568° 



The mean is 569° and for 144 grams it is 81,936°. 



It was shown* that the heat effect of 3Na 2 0,R 2 5 , in which 

 E. is phosphorus, arsenic or antimony, is closely related to the 



Fig. 1. 



180 



140 



100 



60 



II 



Of 



Mo 



W 



atomic weights of these elements. The same relation appears 

 in the sub-group of chromium, molybdenum, and tungsten. In 

 the figure the atomic weights are plotted as abscissas and the 

 heats of combination as ordinates. The line I indicates the 

 heat of the reaction Na 2 0,R0 3 , and II of R,0 3 . 



Molybdenum Dioxide. 



Molybdenum dioxide was made by reducing the trioxide as 

 follows : a 100 cc pipette was weighed, tilled with molybdenum 



* This Journal, vol. xxviii, 103, 1909. 



