186 Miscellani'- 



vain for us to reduce the thickness ol _., w' ^^a to the least possi- 

 ble "film, or even to heat the iron ball to ri uid to pass it slowly 

 over the thernao-multiplier j the index alv::'.ys preserves the most per- 

 fect immobility. 



After the foregoing experiments, it could not be imagined 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 

 bad 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 transJDarent ice ; we ap-^ 

 plied them to the appendices of the therrao-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 heated 

 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 instanta- 

 neous passage of radiant caloric. 



It has been very generally admitted until recently, that insects do 

 not possess a temperature independent of the medium in which they 

 are situated. Notwithstanding, the carbonic acid which is formed in 

 the atmosphere from the action of these little animals, placed beyond 

 a doubt the existence of a slow combustion in 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 introducing 

 the bulb of a thermometer. He perceived that their temperature 

 w'as in general a little superior to that of the atmosphere. Among 

 twelve insects taken from different classes, he found two, the scor- 

 pion and the jidus, whose temperature, instead of being higher, was 

 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 dimensions ; Resides, it did not give the 

 temperature of the animal in tlit) natural state, but in a maimed- and 



