8 THE ROYAL SOCIETY OF CANADA 



in cocoanut charcoal." However, as will be shown presently, this 

 should, strictly, not be called adsorbed hydrogen. 



This experiment in conjunction with the latter part of experiment 

 (1) indicates that at room temperature, the amount of adsorbed 

 hydrogen being greater than at 275° the amount of action of ad- 

 sorbed hydrogen on the remaining nickel oxides, is relatively large, 

 notwithstanding that the temperature is lower. This would indicate 

 that the efïect of adsorption of hydrogen on the reductions is large 

 in comparison with the effect of temperature. 



Experiment 4. 



It was hence desirable to determine whether hydrogen is adsorbed 

 during the reduction of nickel oxide at 275°C. 



3 grams of nickel oxide, without any asbestos, was placed in the 

 tube d. Hydrogen was first passed through the apparatus dis- 

 connected from the burettes, at room temperature for one hour, the 

 tubes c c having been weighed full of nitrogen beforehand. The 

 burettes containing a measured volume of hydrogen were now con- 

 nected with the system and the reading of the burettes taken. The 

 tube d was now heated to 275°C. and hydrogen passed back and 

 forth for one hour. At room temperature the volume of hydrogen 

 used up was determined. In this case 980 c.c. The burettes were 

 disconnected and nitrogen passed for one hour at 120°C. to drive over 

 all the water formed in the reduction. . 6894 g. water was obtained. 

 This is equivalent to 920 c.c. hydrogen. Thus, about 60 c.c. of 

 hydrogen was adsorbed during the reduction to this stage. 



A similar experiment gave water equivalent to 380 c.c. of hydro- 

 gen with an adsorption of 45 c.c. for the set of conditions under 

 which this reduction was carried out. 



Thus, when nickel oxide is reduced at 275°C. hydrogen is adsorbed 

 in very considerable amount over and above the hydrogen used to 

 form water. On cooling to room temperature and allowing to stand 

 several hours in hydrogen very much more is adsorbed, the first 

 portion adsorbed at 275° having gone to reduce more of the nickel 

 oxide. On now heating to 275° in hydrogen relatively very little 

 water is obtained because most of the hydrogen previously adsorbed 

 has been used up in reducing nickel oxide, the resulting water being 

 evolved, and also because the adsorption at 275° on nickel alone, 

 without the accompaniment of reduction of nickel oxide, is small. 



Experiment 5. 



This experiment was performed in order to determine the follow- 

 ing: 



