194 JtiiPfer — Formation of the Oxides of Cobalt and NieTcel. 



stirred up in water with an electromagnet. The weii>ht was 

 noted of tlie metallic cobalt found in a fusion. 



Ea'periment 1. — The platinum electrode in the bomb was a 

 millimeter thick and was about 3'''" above the tray. The end 

 of it melted off at the time of the combustion and dropped 

 into the mass l)elow and alloyed with the cobalt. Hence the 

 gain in weight due to oxygen could not be found and, there- 

 fore, the oxide was reduced by hydrogen. The loss in oxygen 

 was 2'7-l:7 grams. The calorimetric result, 9658° -H 2-747 = 

 3480'-' for 1 gram of ox3rgeu taken up and for 16 gram^; 55,680°. 



Experitnent %. — This test was like the preceding except that 

 a mica tray was used. It was placed lower in the bomb and 

 farther from the platinum electrode, which, nevertheless, melted 

 off. The cobalt oxide was reduced as before. The result for 

 16 grams of oxygen was 55-984°. 



Experiments 3 4 5 



Cobalt..- 12-417 grams 13-027 grams 15-364 grams 



Cobalt unburned 0-793 " 0-507 " 1-631 " 



" burned 11-624 " 12520 " 13-733 " 



Mica tray _.. 0-417 " 0-497 " 0-268 " 



Oxygen taken up .. . 3-088 " 3-340 " 3-706 " 

 Water equivalent of 



system 3,467- "3,535- "3,617- " 



Temperature interval 3-190° 3-396° 3-678° 



Heat effect 11,060 12,005 13,303° 



" of oxidation of iron 50 48 50° 



11,010 11,957 13,253° 



For 1 gram of oxygen 3,565 3,580 3,576° 



" 1 " "cobalt 947 955 966° 



" 16 " " oxygen 57,040 57,280 57,216° 



" 59 " "cobalt 55,873° 56,345° 56,994° 



^ . 3-088 3-34 3-706 



Oxygen ratio = 0-193 = —0-209 = 0-232 



•^^ 16 16 16 



^, , . 11-624 ^ 12-52 13-733 „ „„„ 



Cobalt ratio.. = 0-197 = 0-212 —- = 0-233 



59 59 59 



In 3 all of the metallic cobalt left was in one globule. The 

 oxide obtained in this experiment was pulverized in a steel 

 mortar and the powder stirred up in water with an electro- 

 magnet which removed an insignificant quantity of black par- 

 ticles. Next, 2-8969 grams of the powdered oxide, dried at 

 100°, was reduced by hydrogen, and 2-2800 grams or 78-74 • 

 per cent of cobalt obtained. CoO contains 78-67 and 00,0^ 



