INTRODUCTION. 21 



We are almost ignorant of" the cause of these 

 different conformations. Philosophers assert 

 that not a particle of light can be lost, but only 

 changed by entering into chemical combination 

 with other bodies, and producing, by means of 

 oxygen, a certain acidification of the colourable 

 recipients. Florists have long wished for the 

 power to change, as they could wish, the colours 

 of their flowers. Some approach has been made 

 towards the accomplishment of this desirable 

 faculty in some few cases; and there is no doubt 

 but that, in time, such discoveries will be made 

 as will in some measure invest the florist with 

 this necessary knowledge. 



By art we can change the colours and forms 

 of flowers, and give new qualities to fruit, by 

 the well-known expedient of cross impregnation 

 (which shall be fully described in the sequel) ; 

 but in the case of full flowers, which rarely ad- 

 mit of such manipulation, recourse must be had 

 to other expedients, and which, it is presumed, 

 will sooner or later be furnished by the excellent 

 science of chemistry. 



