596 Journal of the Asiatic Society of Bengal. [December, 1910. 



platinum, ferric oxide and the like. In the case of nickel, 

 Sabatier and Sanderens (Compt. Rend. 14, 1429) have shown 



that when nitric oxide is passed over reduced nickel, nickel 

 oxide (NiO) is formed. We have found that when a mixture of 

 nitric oxide and hydrogen in the proportion of one to three (or 

 better one to four) is passed over heated reduced nickel, almost 

 the whole of the nitric oxide is converted into ammonia, 

 scarcely any nitric oxide coming out unreduced. The reaction 

 commences at about 300°C, and when once the reaction starts 

 the temperature may be lowered to 120 when the reduction 

 continues. At about 300 c the reduction is very rapid and very 

 considerable quantities of ammonia are formed. Blank experi- 

 ments were performed by passing nitric oxide over heated nickel 

 after driving out all the air by means of carbon dioxide and 

 again cooling in a current of the same gas in order to avoid 

 oxygen. It was found that no nitride, nitrite or nitrate of 

 nickel was formed. Thus it is seen that the reduction of 

 nitric oxide takes place directly and nickel acts as a catalytic 

 agent. 



Reduction of Sulphur Dioxide in presence of Nickel. 



When a dry mixture of the two gases was passed over 

 heated nickel, sulphuretted hydrogen was evolved. The reac- 

 tion took place at a dull red heat. The reduction does not 

 seem to take place directly. Geitner (Annalen, 139, 354) has 

 already shown that aqueous sulphurous acid is decomposed by 

 Ni at about 200° with production of Ni s S 4 . By passing dry 

 sulphur dioxide over reduced or electrolytic nickel for six hours 

 even at the ordinary temperature a little nickel sulphide wa§ 

 formed, and when a weighed quantity of such nickel was heated 

 in a Sprengel pump, very small quantities of occluded sulphur 

 dioxide were collected. It seems that sulphuretted hydrogen is 

 formed partly by the reduction of nickel sulphide formed 

 (blank experiments showed that precipitated nickel sulphide is 

 readily reduced by hydrogen when heated , though it has been 

 stated in Watt's Dictionary of Chemistry, vol. hi, " nickel mono- 

 sulphide ' ' , that it is not decomposed by hydrogen) and parth 

 by the reduction of the occluded sulphur dioxide. 



>/ Phosphorous Pentoxide in presence of Nickel. 



Phosphorous pentoxide was first heated in a current of 

 oxygen for several hours in order to oxidise any free phosphor- 



ous contained in it. When 



phos 



phorous pentoxide heated in a tube-heater, no phosphuretted 

 hydrogen was formed. When, however, the pentoxide was mixed 



With redllOpd nioWi ff.VlA T^nfAvirln nrnc. iY*fi.rwli-ir>or1 in thpi tube 



moisture) 



hydrog 



