Caloric by Friction. 373 



small matter that we have exhibited it by experiments, for we are 

 thus supplied with another element, which henceforward may 

 be taken into consideration in the theory of heat. 



If we now inquire concerning the relations which exist be- 

 tween the production of heat and the production of electricity, 

 in the mutual friction of two bodies, the following are the con- 

 sequences which result from the experiments which have been 

 recently made. The displacement of parts of the rubbed surfaces 

 always occasions a disengagement of heat and a disengagement of 

 electricity, — two effects which exert a mutual dependence. This 

 dependence, however, is so much obscured, that it is still im- 

 possible to affirm if the one precedes the other, or vice versa. 

 We can only make conjectures on the point, — conjectures which 

 go to shew that the heat is derived from the electricity, when the 

 bodies are of the same nature, — are bad conductors of caloric, — 

 and only differ as to the condition of their surfaces. The sur- 

 face which is most heated becomes negatively electrified ; and 

 that which is least heated positively. When the bodies are dif- 

 ferent, the effects become more complex, and can be interpreted 

 only when the results are immediately under observation. 



Some facts recently brought under review permit us to group 

 together the relations discovered between heat and electricity, 

 and of which phosphorescence supplies an example. It is known 

 that this phenomenon shews itself wherever particles of bodies 

 which are bad conductors of electricity are disturbed by per- 

 cussion, friction, heat, light, a shock of electricity, or when they 

 are decomposed by chemical action. These causes are precise- 

 ly those which likewise disengage electricity ; and the pheno- 

 mena being atomic, must produce an infinite number of minute 

 sparks which together produce a faint light similar to phospho- 

 rescence. Hence we may suppose that phosphorescence has an 

 electrical origin. 



In glow-worms (Lampyris) and the infusoria, we are igno- 

 rant whence the phosphorescence proceeds, and if it be owing 

 to electricity. The important experiments, however, of M. 

 Ehrenberg are about to instruct us. This able physiologist 

 has lately been studying with peculiar care the light which is 

 emitted in darkness by the infusoria and the annelides which 

 make the ocean luminous in certain countries, especially when 



