Separation and Striatio7i of Rarefied Gases. 



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extremely brilliant. The current was then stopped, and the 

 tube allowed to rest for about an hour, when, the current 

 being passed again, the same phenomenon precisely occurred. 

 Judging that if this were caused by actual separation of the 

 two gases, it ought to be possible to frac- 

 tionate out the hydrogen into another 

 tube, I endeavoured for a long time un- 

 successfully to do so ; but at length suc- 

 ceeded by using a double tube of the shape 

 shown in the figure. The longer of the tubes 

 consisted of two chambers joined by capillary 

 tubing, the smaller tube being connected 

 to one of these by a narrow neck capable 

 of being sealed off. Both tubes were 

 furnished with electrodes. One of those 

 in the large tube was sufficiently long to 

 project through the capillary into the second 

 chamber, and being connected at its base to 

 the sealed platinum by a weak spiral wire 

 could be dropped sufficiently far to touch 

 the opposite electrode. This rod was made 

 of copper, as being heavier than aluminium. 

 It fitted the capillary fairly well, and 

 ^as furnished with small stops of cotton- 

 wool in order to close the capillary, and thus prevent as 

 much as possible the diffusion of the gases. " The tube, 

 after being filled with the gases carbon dioxide and hy- 

 drogen, was exhausted and sealed from the pump. The 

 copper rod was caused to touch the opposite electrode, and 

 the current was passed so as to make the whole of the long 

 tube the negative pole and the electrode at the low T er end of 

 the smaller tube the positive. The current was continued for 

 a considerable time, when the connecting-neck between the 

 tubes was sealed off and the copper rod shaken back to the 

 stop. On comparing the spectra of the two tubes, it was 

 found that the small tube (containing the positive pole) 

 showed only a trace of hydrogen, while the other showed it 

 brilliantly. 



This, 1 think, may be considered a proof of an actual 



I though not complete separation of the two gases. 

 I then tried hydrogen mixed with many other gases — 

 amongst them nitrogen, carbon monoxide, sulphur dioxide, 

 iodine, and mercury vapour; and in every case, without 

 exception, I found that the hydrogen was collected about the 

 negative pole in exactly the same manner as I have par- 

 ticularized. 



