AS OBSEEVED IN TOEEICELLIAN AND OTHER VACUA. 
145 
Eig. 6. 
of the mercury they appeared very briUiant from reflexion. The mercury was then 
allowed slowly to liquefy, and the position of the tube reversed, so as to permit the 
mercury to cover both wires, the larger end of the tube was heated by the spirit-lamp 
until the mercury boiled, passing over to and condensing at the other end. The strati- 
fications entirely disappeared, the discharge passing in a direct line along the tube, and 
illuminating in its passage the lower side. 
79. In the case of the tube represented in fig. 1, 1 have stated that with one cell of the 
nitric acid battery the discharges show two or three broad and distinct 
clouds (72); and if a magnet is brought near the negative mercury, 
eight or ten additional cloud-like stratifications are brought out equally 
clear and defined. In experimenting with this tube, I suspended it, as 
before, with a strong loop ; in this manner it hangs freely in the air, 
the platinum wires being connected to the induction coil in the usual 
manner by helices of thin copper wire. The lower end of this tube was 
inserted in a glass vessel (fig. 6) containing ether to which a quantity 
of sohd carbonic acid was from time to time added ; owing to the large 
mass of mercury, some time elapsed before the metal froze ; when the 
temperature of the ether was reduced to — 85° Fahe., discharges from 
the induction coil being made, the stratifications were no longer visible, 
but a small luminous spot remained at the end of the positive terminal. 
On presenting the north pole of a magnet on one side of this luminous 
spot, or the south pole on the other, another luminous spot was visible, 
and on drawing the magnet down the tube the stratifications came out, 
but not so clearly separated as before. The blue negative discharge 
was perceptible, but not so defined as when the tube is in its normal 
state of temperature. The interior of the tube was progressively lumi- 
nous from the negative mercurial terminal, the luminosity decreasing 
in intensity towards the positive wire. On removing the ether-bath, the 
mercury gradually liquefied; the temperature rose, and at -1-20° Fahk. 
the stratifications reappeared. 
80. Fig. 7 represents a tube similar in form to fig. 4, but having, as in fig. 2, sufficient 
mercury to cover both wires. In this tube the cloud-like stratifications are very clearly 
defined. The white tongue, when the negative wire 
is exposed, is also very distinct, as is also the blue from 
the negative wire. Two glass vessels, containing ether, 
were placed so as to receive the two ends of the tube, 
the wires being covered with the mercury ; solid 
carbonic acid was applied as before, the mercury in 
both ends quickly froze ; on trying the temperature, 
one end indicated — 98° and the other — 102° Fahe.; the surfaces of the mercury, in 
the act of cooling, assumed a concave form, that at a being more depressed than that 
MDCCCLIX. X 
Eig. 7. 
