﻿214 Prof. W. Ramsay on the Passage of 



740 millim. This would appear to indicate that palladium is 

 quite impermeable to cyanogen, and is not attacked by it at 

 280°. 



Experiment 22. — Nitric oxide was introduced into the tube, 

 at a barometric pressure (corrected) of 765 millim. On passing 

 hydrogen the pressure rose 368 millim. ; the total pressure of 

 the gases in the tube was 368 + 763 = 1131 millim., the baro- 

 metric height being 763 millim. The increase of pressure was 

 therefore 1131 — 765 = 366 millim. Supposing that the nitric 

 oxide had reacted with the hydrogen, forming nitrogen and 

 water, thus : — 



2NO + 2H 2 = 2H 2 + No, 



4 vols. 2 vols. 



the pressure of the nitric oxide would have been halved, and 

 would have amounted to 765/2 = 382*5 millim. But it is to 

 be supposed that the resulting water would have exerted its 

 usual vapour-pressure ; and as its temperature was 22°, the 

 pressure of the water-vapour would be 18*5 millim. 



We have thus :— r^n^. 



Pressure of H 2 + N 2 + H 2 vapour . 368 + 763 = 1131 

 Pressure of N 2 + H 2 vapour . . 382*5+ 18-5= 401 



Hence pressure of hydrogen alone = 730 



and the quotient 730/765 = 0*9543, a number almost identical 

 with those previously obtained. 



Experiment 23. — A similar experiment was made with 

 nitrous oxide. Here, too, reduction occurs at 280° ; but the 

 volume of the residual nitrogen is equal to that of the nitrous 

 oxide. 



The initial pressure of the nitrous oxide was 772 millim. 

 After passing hydrogen, the total pressure was 1489*5 millim. 

 The difference, 717*5 millim., is to be ascribed to hydrogen 

 and water-vapour. The barometer stood at 761 millim. 

 Deducting 18*5 millim., the pressure of water-vapour at 22°, 

 the pressure of the hydrogen alone is 699 millim. And the 

 quotient 699*0/761 = 0*9186. 



The hydrogen was then removed by a current of air on the 

 external surface of the palladium. The pressure of the 

 nitrogen was then 780*5 millim. Again restoring hydrogen 

 on the exterior, the pressure rose to 727*5 millim., the baro- 

 metric pressure being 761 millim. The pressure ascribable to 

 hydrogen and water- vapour is thus 708 millim, ; subtracting 

 the pressure of water- vapour, 22*5 millim., the remainder, 

 685*5 millim., is due to hydrogen. The quotient is 0*9008 

 Here again a reasonable correspondence is found. 



