165 



VIII. — On the Identity of Light, Heat, Electricity, Mag- 

 netism, and Gravitation. 



By J. Goodman, M.D., M.R.C.S. 



iRead March %ih, 1852.] 



In my experimental researches into the identity of these 

 forces, I have long sought a great desideratum in Science, 

 viz., an instrument which would give intimation of the pro- 

 gress and transition of caloric along the molecules of matter, 

 or the interior construction of bodies, and I believe that 

 object has been attained in the following experiments. 



From the difference of temperature of bodies, — the facility 

 with which we can increase the temperature of a cold body 

 by the apposition of one already heated, and of cooling the 

 latter also by the same contact, — and frona .a knowledge of 

 the laws of transmission, diffusion, radiation, ignition, coction, 

 fusion, and volatilization, by this force ; — I cannot, in spite of 

 all modern theories upon the subject, and the teaching of the 

 Schools, draw any other conclusion than that this force is a 

 bond fide imponderable existence, possessing the ordinary 

 qualities of matter — locality, extension, impenetrability, 

 resistance, attraction, motion; and, as I believe is shewn 

 in the following experiments, momentum also — a property 

 hitherto applied alone to ponderable matter. 



That heat possesses the three former properties is not ob- 

 jected to by philosophers, inasmuch as it is not contended 

 that it enters into the substance of the atoms or elementary 

 particles of matter, and occupies with matter the same space 



