30 LECTURE I. 



and into rays not calorific, refracted in like 

 manner to the opposite side of the spec- 

 trum beyond the violet colour ; and that 

 the calorific and un calorific rays produce 

 effects similar to those occasioned by the 

 two kinds of electricity ; and thus afforded 

 additional reasons for believing that subtile 

 mobile substances do enter into the com- 

 position of all those bodies which the sun 

 illumines, or its beams can penetrate. 

 Late observations induce the belief, that 

 even light may be incorporated in a latent 

 state with animal substances, and after- 

 wards elicited by a kind of spontaneous 

 separation, by vital actions, or by causes 

 that seem to act mechanically on the sub- 

 stance in which it inheres. * All the late 

 discoveries in science seem to realize the 

 speculations of ancient philosophers, and 

 shew that all the changes and motions 

 which occur in surrounding bodies, as well 

 as in those which live, are the effect of 

 subtile and invisible principles existing in 

 them, or acting on them. 



* See Dr. Hulme's, and Dr. Macartney's papers in 

 the Philosophical Transactions. 



