SURROUNDING MEDIA ON VOf/I'AIC IGNITION. 
5;i 
test. I associated in turn oxygen and nitrogen with carbonic acid; the following 
were the results. In five minutes the thermometer rose — 
In oxygen. In carbonic acid. 
Exp. 1st. From 60° to 7*5°- From 60° to Jb°. 
2nd. 60° to 76°. 60° to 75°. 
In nitrogen. In carbonic acid. 
Exp. 1st. From 60° to 74°. From 60° to 73°. 
2nd 60° to 73°. 60° to 72°-5. 
The battery had in the last experiment a little decreased in power ; the oxygen and 
nitrogen both produced a less cooling effect than the carbonic acid, but the oxygen 
came nearer to it than the nitrogen, thus according with the previous experiments. 
Upon the whole it would appear that oxygen produces a somewhat greater cooling 
effect on the ignited wire than nitrogen, but these gases may, for the purposes of this 
paper, be fairly regarded as equal. Atmospheric air produces a similar effect to 
oxygen and nitrogen separately, though I am inclined to think that a slight chemical 
change takes place when atmospheric air is exposed to the ignited wire, and that 
nitrous acid is formed ; for if litmus paper be held over a voltaically ignited platinum 
wire in the air, a slight but very perceptible tinge of red marks the portion of it im- 
mediately over the wire. 
With the view of ascertaining whether the specific heat of the surrounding media 
w^ere the cause of the phenomenon, I proceeded to try the effect of the wire carrying 
a voltaic current on different liquids ; all things being disposed as in the previous 
experiments, and three ounces of water being associated respectively with the same 
quantity of the following liquids. The thermometer I’ose in five minutes — 
In water, from 60° to 70°‘3. In spirit of turpentine. 60° to 88°. 
In water, from 60° to 70°' 3. 
In sulphuret of carbon 
60° to 87°-l. 
In water, from 60° to 69°. 
In olive oil ... . 
60° to 85°. 
In water, from 60° to 70°T. 
In naphtha .... 
60° to 78°-8. 
In water, from 60° to 70°’5. 
In alcohol sp. gr. 0’84 
60° to 77°. 
In water, from 60° to 68°-5. 
In ether 
60° to 76°-I. 
I do not much rely on the last experiment, — the battery was in more feeble action ; 
and though each of the above results is the mean of three experiments, yet the 
variations in the results of the different experiments with ether being considerable 
(while in the others they were very trifling), lead me to place no great dependence 
on it. The rapidity of evaporation and the readiness of ebullition of the ether re- 
quire that a larger quantity should be used; but as this for the purpose of compa- 
rison would have required all the experiments to be repeated with different quantities 
