Dialytic Separation of Gases by Colloid Septa, 525 



4. The same mass of gold cornettes heated in hydrogen gas 

 gave up afterwards in one hour 2'7 cub. centims. of gas, which 

 appeared to consist of 



2*34 cub. centims. Hydrogen. 

 0-36 „ „ Nitrogen &c. 



¥70 



The power of this metal to occlude hydrogen gas is very 

 sensible. The metal here appears to hold 0*48 volume of hy- 

 drogen gas. The same gold, when dissolved and precipitated, 

 was also found capable of holding 0*44 volume of hydrogen. 



5. The same mass of cornettes, heated in carbonic acid gas, gave 

 up afterwards in one hour 1*05 cub. centim. gas in which baryta- 

 water showed the presence of 



0*78 cub. centim. Carbonic acid. 

 The charged cornettes were always freely exposed to air for 

 some time before occluded gas was extracted from them and 

 measured, so as to allow the escape of any loosely attached gas. 



6. The same cornettes were heated and cooled in a stream of 

 dry air, in like manner as they had been treated with other 

 gases. The occluded air given out in one hour amounted in 

 two different experiments to 1*15 and 0*95 cub. centim. respec- 

 tively. The gas of the second experiment gave 



0'82 cub. centim. Nitrogen . = 86*3 

 0-08 „ „ Carbonic acid = 8*4 

 005 „ „ Oxygen . = 5*3 



0-95 10O0 



The whole occluded air amounts to 0*2 volume of the gold, 

 and is principally nitrogen. The indifference of gold to oxygen 

 is remarkable, and contrasts with the power of silver to occlude 

 the same gas. 



Silver. 



1. Fine silver in the form of wire, 2 millims. in diameter, 

 with its surface duly purified, was first heated alone in the por- 

 celain tube, and then exhausted of gas by the Sprengel tube in 

 the usual way. The natural gas derived from this metal was 

 small in quantity, and it appeared to come off almost entirely in 

 one hour. The silver wire weighed 108*8 grms., and had a 

 volume of 10*37 cub. centims., taking the specific gravity of 

 pure silver as 10*«49. The gas extracted amounted to 



2*2 cub. centims. in thirty minutes. 



0'8 » » » 



3'0 „ ., in one hour. 



