276 Prof. Norton on Molecular Physics. 



rate perceptions. We have an example of a similar physiological 

 fact in the sense of hearing. Although we receive the sound 

 from two organs in opposite directions, only one perception is 

 felt by the mind ; the two sensations, like two drops of water the 

 moment they reach each other, are resolved into one. 



If, for such a trifling subject, I have encroached so much on 

 the time of the Meeting, I have to offer an excuse which, I hope, 

 will be kindly accepted. How is it possible to be short when 

 one principle of science irresistibly leads us to another ? and 

 how can we stop when we begin to unfold the marvellous and 

 innumerable expedients which the Creator has employed to make 

 our senses perfect and to help our intellect ? 



XXXVII. On Molecular Physics. By Prof. W. A. Norton*. 



[Continued from p. 113.] 



n^HERMO-ELECTRICITY.— The key to thermo-electric 

 phenomena should be found in the effect produced by heat 

 on the electric condition of molecules. Now when heat is applied 

 to a surface, the molecules at the surface first receive the ethereal 

 pulses of which the force of heat consists. These pulses passing 

 on to the central atom of each molecule, or the condensed uni- 

 versal sether at the centre of the molecule, are there partially ex- 

 pended in expanding its electric atmosphere on the other side, and 

 are partially propagated on. Upon reaching the inner side of the 

 atom they will again be partially consumed in expanding the 

 atmosphere on that side, while a certain portion will be trans- 

 mitted to the next atom. It is easy to see that this second expan- 

 sion should be less than the first. Under these circumstances two 

 important electrical effects will be produced. (1) By reason of the 

 greater expansion of the atmosphere on the outer than on the inner 

 side, its density will be diminished on the outer side, and hence 

 electric sether will flow around to that side. The molecular atmo- 

 sphere will therefore become polarized positively on the outer side. 

 (2) As a consequence of this polarization, the molecular atmosphere 

 will urge away from it a portion of the electric at her posited near its 

 surface, and tend to develope a negative polarization in the particles 

 of contiguous surfaces. The surface receiving the heat will then 

 'become positively polarized, and there will be at the same time an 

 electric movement outward from the surface. Cold, or the abs- 

 traction of heat, will have precisely the opposite tendency ; that 

 is, a surface in the act of cooling will become negatively polarized, 

 and this change will be attended with a flow of electricity toward 

 the surface. Such movements of the electric sether will be in 



* From Silliman's Journal for July 1865. 



