184 Mr Kemp’s Experiments on Galvanism. 
liquid nitrate of potass ; and at the instant of contact the needle was 
powerfully affected, which evidently showed that the simple galva- 
nic circle had been ‘completed, and that electricity was circulating 
along the wire. 
In this experiment the whole of the substances used for generating 
the galvanic fluid were at a red heat. 
The crucible was afterwards removed from the furnace, while the 
circuit remained completed. As the temperature of the ‘substances 
decreased, the effect produced on the needle was likewise lessened, 
and almost no effect was perceptible after the temperature of the ni- 
trate of potass fell below a red heat, although it retained the liquid 
State. 
In this arrangement the current of electricity circulated from the 
copper to the lead. 
This experiment was varied by using fused carbonate of potass, 
with the same metals, instead of the nitrate as formerly: the effect on 
the needle; as I had anticipated, was much less than that produced by 
the nitrate. This difference may be accounted for, from the difficulty 
with which the carbonate of potass parts with its oxygen, and the 
consequent decreased action on the surface of the metals. The effect 
produced by the carbonate of soda, when used in the same manner, 
was rather more powerful than the carbonate of potass. 
I now used borate of seda in place of the salts used formerly, ae 
with the same metals, viz. lead and copper, and I found the effect on 
the needle to be more powerful than that produced by any of the salts 
I had previously employed, although the quantity of oxide formed on 
the surface of the metals must have been less than that produced by 
the nitrate of potass. It may, therefore, have been owing to the 
borate of soda requiring a less degree of heat to bring it into a “perfect 
state of fusion than the other salts, and thereby be rendered a better 
conductor of electricity than those in a less perfect state of liquidity. 
With the same apparatus these experiments were farther varied, 
by using, instead of the lead, other metals, as tin, zine, brass, copper, 
and iron ; with the liquified tin, zine, and brass, I used a plate of 
copper, and with liquified copper and iron a plate of wrought iron. 
As an exciting liquid between these metals, 1 employed the nitrate 
and carbonate of potass, and the carbonate of soda, and also the borate 
of soda. 
The effect produced on the needle by the use of melted tin was less 
powerful than that produced by lead ; and the same ratio of power 
appeared to hold with respect to the different salts, as in the first 
experiment, when the lead was used. 
With liquid zinc and nitrate of potass the effect was also rather 
powerful, but not nearly so much so as would have been supposed, - 
from the quantity of oxide formed on the surface of the metal, as the 
thickening of the nitrate apparently rendered it incapable of trans- 
mitting the electric state so easily. With the other salts the effect 
was nearly similar to that produced by the metals used formerly. 
When liquid brass was used, the effects were much similar to those 
of zinc. 
