GALVANISM. 
cnlar was the cure of perfect loss of speech. 
If the naked metal of the wire, from a pow- 
erful battery, be applied to the skin, it be- 
comes cauterized and blistered. 
If the plate, covered with a moistened 
sponge, connected with one end of the bat- 
tery, be applied to the back of the head, at 
the same time that the moistened fingers of 
one hand are slightly applied to the other 
end, a smarting sensation will be felt in the 
part, and a taste at the same time will be 
felt in the mouth, similar, but in a greater 
degree, to that occasioned by the piece of 
zinc, and the shilling when laid upon the 
tongue. This experiment succeeds the 
best with a small number of large plates, as 
much as ten inches square. 
Decomposition of Water and other Bodies. 
The most simple way of performing this 
experiment, is to bring the wires coming 
from each end of the battery into a vessel of 
water. A profusion of bubbles of gas will 
appear to be given out from each wire, as 
far as they are immersed in the liquid. The 
nearer the wires are brought together, so as 
not to touch, the more rapidly the decom- 
position goes on. The gas produced from 
the wire coming from the zinc end of the 
battery, if the wire be of gold or platina, 
is found to be oxygen gas ; but if the wire 
be of any more oxydable metal, no gas will 
appear, but the wire becomes oxydated. 
The gas furnished by the wire from the 
copper end of tire battery, of whatever kind 
of metal the wire may be, is pure hydrogen. 
If the immersed part of this, however, be 
previously oxydated, no gas will be ob- 
served for some time, the hydrogen being 
employed in reducing the oxide upon the 
surface. 
Both the gases are furnished from the 
decomposition of the water. 
An apparatus more convenient for this 
experiment, and at the same time fitted for 
collecting the gases, is shewn in fig. 4 ; c g, 
is a cup of glass capable of receiving the 
glass tube, h ; E c, and/s, are two wires of 
platina, fitted into two holes perforated in 
the bottom of the glass cup ; the tube, h, 
which is close at the top, is first filled with 
the water or other liquid, and the cup in- 
verted upon it ; the whole are then suddenly 
returned into their erect position: this ap- 
paratus is then placed in the frame, fig. 5 ; 
A B C D are four pieces of brass, united to- 
gether by the pieces of glass, F and G, and 
supported by four legs, through which also 
the brass rods, H and K, are passed. It is 
plain, the two sides of this frame are insu- 
lated with respect to each other, at least 
as much as is necessary for any galvanic ex- 
periment. The part/, in fig. 4, being in- 
troduced into any of the holes, such as n m, 
the opposite end, F, is made to rest on 
the opposite brass rod, K. If the wires 
from the battery be now connected with 
the frame at H and K, the gas will instantly 
begin to rise from the wires, c and z, up in- 
to the tube, while the liquid descends and 
occupies the cup. 
A number of the apparatus, such as fig. 4, 
may be employed at the same time; and if 
the different tubes are filled with different 
liquids, such as the various solutions of salts, 
and the communication of each occasionally 
cut off, by placing some non-conductor at 
E, their relative conducting powers may be 
ascertained. 
If two tubes of smaller size be placed, 
one over the wire, z, and the other over 
that of «, the gases may be collected sepa- 
rately. 
If the tube contains a metallic solution, 
such as silver, lead, or copper, the wire 
from the copper end of the battery will af- 
ford no gas ; but the metal of the solution 
will be reduced. Let the glass vessel A, 
fig. 6, have the two tubes, z and c, ground 
into its two necks. At the ends, z and c, 
of the tubes, are tied bits of bladder, so 
that any liquid in the tubes may have no 
tendency to enter the vessel A. The ves- 
sel being previously filled with some liquid, 
the tubes are so inserted that no air may 
exist between the ends of the tubes ; the 
tubes are also provided with two small 
caps of ivory or wood, through which the 
platina wires, pp, are passed, reaching the 
bottom so near as not to pierce the blad- 
ders. The tubes being filled with water, 
and the wire from the zinc-end of the bat- 
tery connected with the wire of tube z, 
while that of the copper is attached to that 
of tube c, the decomposition of water will 
speedily commence, the wire in z affording 
oxygen gas, while that of c affords hydrogen 
gas. In a very short time, the liquid of the 
tube, z, will be found to contain muriatic 
acid; or rather, the oxy-muriatic; hnd the 
tube, c, will at the same time be found to 
contain a fixed alkali. If the tubes be fill- 
ed with infusion of cabbage, the signs of 
alkali and acid are very soon observed, 
from the liquid of z becoming red, and that 
of c green. If the connection be reversed, 
the liquids repass to the blue colour, and if 
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