IV 



PAGE 



8. Of the principles of the ehy mists 6 



9. Objections to them - 7 

 10, What is the primary element of all things ilk 



CHAP. IV. 



Of those Things wherein Natural Bodies differ. 



1. Of the particular properties of bodies - 9 



2. Of light * ib. 

 Particles of light attracted by those of other 



bodies - 10 



Rays of light differ in various respects - n 



The effects of light and sound - 14 

 Remarkable account of the effects of music on 



animals - - 15 



The density of light - 16 



Of elementary light J . 17 



' The inconceivable extension of light - 19 



Of natural and artificial phosphor! : their surprising 



properties - - -20 



3. Of colours - 22 

 Of secondary colours : with curious experiments 



thereon - - 23 



4. Of sounds - 25 



5. Of smells - 26 

 Mr. Boyle's account of smells ib. 

 Fatal instance of the effluvia of flowers 27 

 Effects of the effluvia of springs in England and 



abroad - - ib. 



