48 TRANSMISSION OF HEAT GOVERNED BY REFRACTION. 



principle, it should first have accumulated, and Lave been 

 retained in the conducting metallic wire of greater area, 

 until it had been elevated to an equal temperature with the 

 smaller metallic wire which it had fused. 



The existence of light, radiant and visible in the one in- 

 stance, and latent and invisible in the other, while in a state 

 of apparent quiescence pervading all matter generally, in the 

 several forms of which it is susceptible, is (it would appear) 

 quite sufficient to produce all the sensible phenomena of heat, 

 without the necessity of presupposing the existence of the 

 complex action of a second subtile, imponderable, elastic fluid, 

 for the sole purpose of affording that expansion of bodies, by a 

 separation of their constituent atoms, while under the process 

 of reduction from the solid, fluid, or gaseous state, to that of 

 radiant matter, when the whole can be so easily effected by 

 light itself, by the separation and subsequent union of its 

 constituents, visibly or invisibly, by the forces of electricity, in 

 the proportionable intensity which the circumstances of the 

 re-solution, or combination of the matter then under process of 

 nature, or art, may demand. 



Professor Faraday has discovered that many bodies which 

 in the solid state do not conduct electricity, acquire that pro- 

 perty when they become fluid, and are then immediately de- 

 composed ; and this has induced him to suspect that the power 

 of conduction is simply a consequence of decomposition. 



The learned Professor further shows, that when a non- 

 metallic solid is reduced to a fluid, it nearly loses its power 

 of conducting heat, while it acquires that of conducting elec- 

 tricity in a very sensible degree, giving a new proof of the 

 connexion between heat and electricity. 



The general law by which glass and liquids, and other un- 

 crystallized bodies, possess the property of instantaneously 

 transmitting heat in proportion to their power of refraction, has 

 been established by M. Mellone. 



The same learned philosopher found, that the coloring 



