154 ME. aASSIOT ON THE STEATIEICATIONS IN ELECTEICAi DISCHAEGES, 
100. I have already alluded to the difficulty of obtaining separate carbonic acid vacua 
in which the stratified discharge presents in all respects precisely the same appearance , 
and in order that I might examine the discharge with protected as well as non-protected 
negative terminals yi vacua made under precisely the same conditions, I had two glass 
tubes constructed. No. 101, fig. 14, represents one, a carbonic acid vacuum-tube, with 
Eig. M. 
caustic potash inserted in the narrow portion CP ; the wire A can, by mclining the tube, 
be dropped into the inner case of brass tubing C, which is itself protected by a glass, 
tubing G; the brass tubing is soldered to a platinum wire P, and thus hei-meticaUy 
sealed; B, the other wire, which is fixed, is also of brass. When both wii-es ai-e exposed, 
the stratified discharges show the clear cloud-like appearance so often described, whether 
A is positive or negative; but if A is made negative and the tube is inclined so as to 
let the wire drop into the brass tubing, almost all trace of stratifications immediately 
disappear, that which remains being evidently due to the portion of wu'e and the brass 
tube which is exposed through the orifice ; in this state each discharge is accompanied 
by a ringing noise from within the brass tube : reversing the direction of the dischaige. 
A becomes positive and B negative ; the stratifications are immediately perceivable, and 
the ringing noise in the brass tube ceases. 
101. In the other tube. No. 104 (fig. 15), four wires are hermetically sealed ; a, a ai-e 
Eig. 15. 
exposed ; b, V are protected by being placed in glass tubing, extenduig about one-eighth 
of an inch beyond the points of the metal. When discharges oie taken from a to o', or 
when b or b' is positive and a or o! negative, the stratifications are clear- and distinct; 
and by heating the potassa they can be altered from the cloud to the conical shape ; but 
under whatever condition the tubes may be, the stratifications entii-ely cease if b or U is 
made negative; in this condition no trace of stratifications can be observed, the negatm- 
discharge issuing through the orifice as f rom a jet. 
102. In vacuum-tubes, particulai-ly in some obtained by the carbonic acid process, I 
Philosophical Society of Manchester, the former geutlemau aUuded to the remarkable difference in the 
effects of positive and negative electrifications. 
