UPON THE DIFFERENTLY COLOURED RAYS OF LIGHT. 13 



40. Ether. 



Ether seems to have the same action upon green light as al- 

 cohol. 



4k Fennel-seeds, Sweet, Oil of. 



This oil acts much less powerfully upon green light than 

 flint and crown glass:, and less powerfully than oil of dill 

 seed. 



42. Fenugreek, Oil of. 



This oil acts less powerfully upon green light than flint and 

 crown glass. 



43. Fluor-Spar. 



Fluor-Spar acts less powerfully upon green light than sulphu- 

 ric acid and the white of an egg. 



44. Glass, Crown. 



Crown-glass acts more, powerfully upon green light than 

 flint-glass, oil of spermaceti, oil of olives, oil of ambergris, copal, 

 or oil of juniper. 



It acts less powerfully upon green light than gum Arabic, al- 

 cohol, topaz, fluor-spar, the acids, roclc-crystal, and zvater. 



45. Glass, Flints 



Flint-glass acts less powerfully upon green light than oil of 

 spermaceti, oil of olives i oil of ambergris, essential oil of juniper, 

 oil of rape-seed^ crown-glass, &c. 



It acts more powerfully upon green light than Canada bal- 

 sam, and almost all the essential oils, excepting those expressly 

 mentioned 



When 



