Mixter — Formation of the Oxides of Cobalt and Nickel. 199 



The writer's results, on the contrary, are practically alike, thus: 

 Co + O = CoO(crystalline) + 57,400='andNi, + O = Ni,O + 57,900<=. 

 As the nickelous oxide was sintered together and partly fused, 

 it is compared with crystalline cobaltous oxide and not the 

 amorphous form. 



Nickel does not burn well enough with sodium peroxide to 

 give a satisfactory result. The amorphous nickelous oxide is 

 more finely divided than the metal and appears to burn better, 

 but it is impossible to interpret a thermal result without other 

 data. 



Zinc. 



6. Heat of reaction of zinc with sodium, peroxide. — Zinc 

 powder free from oxide was made by chipping off the metal 

 on a lathe with a flexible chisel. A mixture of the powder 

 and sodium peroxide burns when ignited by a hot wire with 

 explosive violence and in a bomb yields a fused mass. Three 

 combustions were made with the following mixtures : 



1 

 Zinc taken 8-010 



" not oxidized 0-0'72 



" oxidized T'OSS 



Sodium peroxide. 10- 



Heat effect of 1 gram of zinc 1,02 1<= 1,048"= 1,033° 



The mean, 1033 X 65-1: = 67,600^ from which the heat of 

 formation of sodium zincate is derived, is as follows : 



Zn + Na,0, = Na,ZnO, + 6'7-6<= 



Na O + O = Na O, + )9-4<= 



3 



3 



10-575 



10-580 grams 



0-054 



0-047 " 



10-521 



10-533 " 



15- 



15- 



Zn + O + Na,0 = Na^ZnO, + 87-0= 



DeForcrand*' prepared compounds which may be regarded as 

 hydrated peroxides of zinc or zinc oxide and hydrogen peroxide, 

 as for example TaW^^^ + 2H,0 or 3ZnO + 211,0,.' Hence the 

 question — Was a peroxide formed in the fusions described ? 

 Evidentl}' not, since in experiment 1 9-4 grams of sodium 

 peroxide were required to form zinc oxide, and in 2 and 3, 12-6 

 grams. 



DeForcrandf calculated the heat of formation of zinc oxide 

 from the observations of other investigators, taking the atomic 

 weight of zmc as 65, and obtained the following : 



* Ann. de Chem. et Phys. [7], xxvii, 26. 

 fLoc. cit. 



