360 M. E. Goldstein on Electric Discharges 



distinguishable on the other side towards the metallic negative 

 electrode, owing to the great length of the column of light. 



24. I may be allowed to draw attention to the fact that the 

 laws which regulate the character of discharge through each 

 part of the tube {cf. also nn^ pa})er already referred to) enable us 

 to predict all phenomena which tubes of any complicated shape 

 and form may present under any pressure, as soon as the 

 phenomena are known which are presented by tubes having 

 the form of the parts which make up the tube under con- 

 sideration. 



The knowledge of the phenomena seen in tubes which have 

 the form of cylinders, spheres, or ellipsoids is sufiicientto pre- 

 dict everything that can be seen in all tubes which have hitherto 

 been made, in the most complicated ornamental tubes as well 

 as in simple spectral tubes. I reserve a more detailed expla- 

 nation and application of the facts. 



25. If a cylinder is divided into one part containing the ne- 

 gative pole and into several other similar parts communicating 

 with each other by small holes, each part will behave like a 

 separate cylindrical tube. At its negative pole it will give out 

 hght which has all the properties of the negative light ; and 

 the remainder of the part will be filled with positive light up 

 to the secondary positive pole. If the light is stratified, we 

 must number the stratifications in each part separately. 



If we fill, for instance, the tube with a gas showing strati- 

 fications (say, hydrogen), we obtain effects like those described 

 above — stratifications showing different columns, and columns 

 of stratification made up of parts of different colours. 



The colour and form of the different stratifications, how- 

 ever, repeat' themselves exactly in the same order in every 

 part. Each stratification in each part corresponds to ano- 

 ther stratification in every other part which has the same 

 properties as regards colour, brightness, size, &c. The cor- 

 responding stratifications are those which have the same 

 number. Stratifications of the same number, and only those, 

 are entirely alike. 



26. It also follows that by introducing a series of rapid 

 changes in the cross section the dark space which has hitherto 

 only been observed near the negative electrode can be obtained 

 as often as we like*. By choosing a suitable shape of tube, 

 we can make the electric discharge pass in a non-luminous 

 path through almost any distance. 



In a tube 30 centims. long, 25 centims. may be, for instance, 

 entirely non-luminous if the tube consists of a short part con- 



* In a so-called fimnel-tube Foggeudorff lias already observed a series 

 of dark spaces (Pogg. Ann. \ol. cxxxiv. p. 2). 



