152 MR. G-ASSIOT ON THE STEATIEICATIOXS IX ELECTRICAL DISCHARGES. 
th6S6 9.16 strongly atFcctod by induction as th© band approaches tbe glob©, presenting a 
very striking appearance ; there is a shght tinge of red, sho^ving that a veiy minute 
(Quantity of air remains the clouddike stratifications €cc1j€'/id/ to tli6 cfitii 6 di(iTH€t6i oj^ tTi€ 
vessel. 
95. Fig. 11 represents another form of apparatus. This glass tube, Xo. 81, is 12 inches 
long, and about 1 inch internal diameter it has a glass division in the centre, perfoiated 
with a hole about -^th of an inch in diameter, my object being to ascertain in what manner 
the stratified discharge would be affected during its passage through the aperture ; the 
wires are 10 inches apart. I had ah’eady ascertained that if an electrical discharge 
passes through a vacuum-tube a portion of which is of very smaU dimensions, the glass is 
Fig. 11. 
very much heated, while that portion of the glass which is udder remains cool. In the 
apparatus fig. 11, if a is positive and h negative when the discharge shows narrow striae, 
those near the diaphragm in the a positive side are indistinct, while on the h negative 
side the striie are very clearly defined, although the luminous portion is much conriacted; 
when the discharge has assumed the cloud-like appearance, the apertui-e only affects them 
by contracting the cloud, which passes immediately through it. In this tube I had at one 
time succeeded in entirely insulating the discharge, the same as in both those in which 
sulphur and selenium were placed (86), (87), and I subsequently repeated this experi- 
ment with the same tube in the presence of Dr. Frankland and his assistants, in his 
laboratory ; but a few days afterwards, on heating the potash, the discharge returned 
to, and has ever since retained the cloud-like appearance, 
96. I had always found there was apparently much less deposit on the sides of the 
o-lass from brass than from platinum whes ; this was so decided, as to make me doubttul 
whether this deposit was not in all cases due to the platinum to which the brass u-u-e is 
attached. In a tube. No. 82, with brass terminal wires, on the interior of which, from long 
continuance of the discharge, I observed much deposit had taken place, on examination 
Dr. Frankland found this deposit was entirely brass in a minute state of dirision. tiic 
metal being deposited precisely the same as the platinum (37), translucent when 
examined by direct light, but presenting by reflected light a dark metallic lustre. 
Condition of Discharge at Negative Terminal {contimied). 
97. That the stratified discharge is considerably influenced and modified by the pai'ti- 
cular condition of the negative terminal in a vacuum-tube, is erident by the experiment. 
Avhere it did not appear when new platinum vnves AA^ere used, until such AAires were 
corroded by continuous discharges (74). I have also invariably found that if brass Avire 
