362 M. E. Goldstein on Electric Discharges 



The facts described in the three following paragraphs follow 

 from this statement. I always mean by negative or positive 

 pole secondary as well as primary poles. 



30. The limit of the positive light is independent of the po- 

 sition of the positive pole^ and therefore also of the distance 

 between the two poles. 



31. Shifting the negative pole in the direction of the dis- 

 charge produces a shitting of all stratifications in the same 

 direction ; in cylindrical tubes each stratification moves through 

 the same distance. 



If the negative pole is moved towards the positive pole, as 

 many stratifications disappear as were placed in the length 

 through which the negative pole was moved ; if the distance be- 

 tween the positive stratifications is constant, which is generally 

 approximately the case, the number of the disappearing strati- 

 fications are equal to the number obtained by dividing the 

 length through which the negative pole was moved by the 

 distance between the stratifications. On moving the negative 

 pole away from the positive pole, the same number of stratifi- 

 cations reappear. 



32. A movement of the positive pole produces also an ap- 

 pearance or disappearance of stratifications ; but in this case 

 the stratifications themselves remain stationary. 



If the positive pole approaches the negative pole to a dis- 

 tance smaller than that between the negative pole and the first 

 positive stratification, the positive glow disappears altogether. 



33. It follows that tubes may be prepared which do not 

 show any positive light ; the negative light is surrounded by 

 the dark space, which reaches to the positive electrode, and 

 which often takes up the larger portion of the tube. 



We may have either tubes which show this phenomenon 

 only at one particular pressure, or at all pressures, according as 

 the distance between the electrodes is smaller than that at 

 which a stratification may appear for one pressure only or for 

 all pressures. 



34. On exhausting a tube, the stratifications get longer, just 

 as the negative light is known to get longer. At the same time 

 the distance between the stratifications is increased. Both 

 changes seem to go on without limit, and cause the appear- 

 ances described in the two following paragraphs. 



35. With decreasing pressure all stratifications move towards 

 the positive pole, and the sti'atifications decrease in number, 

 disappearing one by one at the positive pole. If the tube is not 

 sufficiently wide to show stratifications along its whole length, 

 the unstratified light moves bodily towards the positive pole^ 

 just as if it were stratified. 



