if 
186 Miscellanies. 
vain for us to reduce the thickness of the stratum to the least possi- — 
ble film, or even to heat the iron ball to redness, and to pass it slowly 
over the thermo-multiplier ; the index always preserves the most 8 
fect immobility. 
After the foregoing experiments, it could not be cnidiehiasl that this 
singular property of water should be owing to its fluidity ; since the 
alcohol, the oil, and the nitric acid, all partake of the same physical 
constitution, while they conduct’ in a manner totally different. We 
had a right therefore, to attribute the effect to the chemical constitu- 
tion of water. Nevertheless, we were disposed to resolve the ques- 
tion directly, by performing the experiment upon solid water. With _ 
this intent, we took two thin layers of very transparent ice ; we ap- 
plied them to the appendices of the thermo-multiplier, which, in the 
present instance, were two equal cylinders. By this means, the ra- 
diation towards the ice being the same on both sides, the needle as- 
sumed the place of zero.on the scale. We then presented the h 
ball at a little distance from the upper layer of ice; the needle expe- 
rienced no alteration in its position. 
These experiments, which we have repeatedly made, show, in- the 
most satisfactory manner, that water owes to a peculiar property, de- 
pendant. upon the nature of its molecules, the remarkable exception 
which it presents among transparent bodies of assisting the inte 
neous passage of radiant caloric. 
It has been very generally admitted until recently, that inseets do 
Not possess a temperature independent of the medium in whieh | 
are situated. Notwithstanding, the carbonic acid whieh 1 is formed § io 
the atmosphere from the action of these little animals, f re 
a doubt the existence of a slow combustion jn the interior of their 
bodies,—a combustion which must of necessity give rise to the extri- 
cation of heat. This has in fact been demonstrated of late through | 
the experiments of John Davy, who measured the temperature | of 
several insects by making incisions into their bodies, and m 
the bulb of a thermometer. He perceived that their temperature: 
was in general a Jittle superior to that of the atmosphere. Among 
twelve insects taken from different classes, he found two, the er 
pion and the julus, whose temperature, instead of being higher, ws 
2° below that of the surrounding air. The method of Davy was 
unsatisfactory, inasmuch as it was inapplicable to all insects, except 
such as possess extraordinary dimesisions ;_ besides, it did not che 
temperature of the animal in the natural state, but ina and 
