W. A. Norton on Molecular Physics. 63 
sides, under the influence of the same amount of heat. If this 
admitted we have a complete explanation of the electric phe- 
nomena exhibited by the tourmaline when heated, in accordance 
with the principles already laid down. Thus, let a tourmaline 
be heated regularly, that is, so that all points of its surface shall 
receive equal increments of heat; at all points of the surface the 
unequal expansive action of the heat upon the two sides of the 
molecular atmospheres in the axial direction, will determine 
their polarization, and an attendant electric movement from the 
positively polarized side of one molecule to the negatively polar- 
ized side of the next. There should accordingly be opposite 
electrical states manifested at the ends of the crystal. This state 
of things should continue so Jong as the temperature is rising. 
But it is to be observed that the effective polarization determined 
in each molecule by the heat is weakened by the discharge that 
takes place from one molecule to the next, and that from this 
s 
than they would otherwise be. Now if the heated tourmaline 
a regularly, the process that attended upon the heating 
will be reversed, and the electrical states, or effective poles, 
P ; : , 
the tension of the universal ether lying between the wires. A 
similar effect, but less in amount, will be produced upon the 
