202 Mr. E. C. C. Baly on tlw Separation and 



I proceeded to examine mixtures of other gases. With 

 carbon monoxide and carbon dioxide, the carbon monoxide is 

 separated out and appears in the negative glow. With 

 carbon dioxide and nitrogen the carbon dioxide is separated 

 out, while the nitrogen remains in the tube, the separation 

 being remarkably distinct. In this case it is the heavier gas 

 which is separated out ; and the same is found with carbon 

 dioxide and sulphur dioxide, the sulphur dioxide appearing in 

 the negative glow. 



It would thus appear that the separation of two gases does 

 not depend on their relative molecular weights. On ex- 

 amining a tube of air, however, the components of which are 

 of fairly equal molecular weight, a separation was found to be 

 very difficult, and only occurred after carrying the exhaustion 

 to a much higher point than was usually necessary. The 

 nitrogen remained in the tube, and the negative glow gave a 

 spectrum presumably oxygen; I say presumably, for I am 

 unable to see what else it can be. 1 was unable to produce 

 the same spectrum in a tube with oxygen, but I was prevented 

 from proceeding farther. The spectra of oxygen Professor 

 Schuster has shown to be very varied under different con- 

 ditions. Is it not possible that the two spectra in an oxygen 

 tube, the banded one in the negative glow, and the bright- 

 line one in the rest of the tube, may be due to separation of 

 two gases? 



From these experiments it is evident that when the elec- 

 tric current is passed through a rarefied mixture of two gases, 

 a process similar to electrolysis is set up, one of the gases 

 being separated out and collected about the negative pole, the 

 other gas remaining in the tube; the proof being that the gas 

 separated out may be fractionated into another tube by the 

 method I have above described. In pursuing these experi- 

 ments I was struck by the apparent close connexion between 

 separation and striation ; that is to say, I found strongly 

 marked striae when there was good separation, and feeble striae 

 when the separation was difficult; I also found that the first 

 appearances of these phenomena were coincident, the forma- 

 tion of striae being always the sign of the commencement of 

 separation. There were no exceptions to this, the action in 

 all the tubes I made being the same. 



It was evident to me that, if the connexion were real and 

 the separation of the gases could in some way be prevented, 

 by avoiding the negative glow, striae would not be formed. 

 I accordingly made a tube the negative pole of which did not 

 protrude from the little glass collar in which it was placed, 

 the positive electrode being made as usual. The tube was 



