q 6S Mr. Children’s experiments 
relations to each other, in this circumstance, seem to be affected 
by elevation of temperature. It may be observed, that the 
order of the above metals, as conductors of electricity, nearly 
follows that of their powers to conduct heat. 
In an experiment in which equal lengths of two platina 
wires, of unequal diameter, (the larger being ~, the smaller 
of an inch,) were placed together in the circuit parallel to 
each other, the thicker wire was ignited, because it conveyed 
more electricity without proportional increase of cooling sur- 
face. When connected continuously, the order of ignition 
was reversed. These two results were foreseen by Dr. Wol- 
laston, who suggested the experiments. 
The experiments which I now proceed to mention, were 
made with the battery in a high state of excitation; and I 
consider them as representing nearly the maximum of effect 
which it is capable of producing. As the quantity of acid 
was increased from time to time, and that previously added 
often almost spent before fresh was put in, it is not easy to 
say exactly what proportion it bore to the water ; perhaps 
the largest may be stated at about 33th. On as on 
former occasions, I found a mixture of nitrous and sul- 
phuric acids, to produce the most powerful and permanent 
effects. 
Exp. i. 5 ft. 6 in. of platina wire, of an inch in dia- 
meter, were heated red throughout, visible in full daylight. 
Exp. 2. 8 ft. 6 in. of platina wire, of an inch in dia- 
meter, were heated red. 
Exp. 3. A bar of platina £ of an inch square, and 2± inches 
long, was also heated red, and fused at the end ; and, 
Exp. 4, a round bar of the same metal, yj yy of an inch 
