l62 Mr. Delaval on the Catije of the 



from which alone any clear illuflration of fuch 

 queftions can be attained. 



For this purf)ore, I entered upon a feries of 

 experiments, which have been performed with 

 Tranfparent Coloured Liquors, and Glafles, as 

 well as with opake, and femitranfparent bodies. 



I fhall, in the firft place, confider Tranfparent 

 Coloured Subflances ; becaufe they are of the 

 fimpleft kind, as they confill only of the Colour- 

 ing Particles united with, and diffufcd through- 

 out, Tranfparent Media, fuch as fpirit of wine, 

 oil, water, or glafs. 



From the examination of fuch tinged media, 

 I have been enabled t6 difcover feveral proper- 

 ties of Coloured Matter, which are very different 

 from thofe, which have hitherto been thought to 

 prevail. 



For inftance, it will appear from the experi- 

 ments which I {hall relate in the fequel, that in 

 Tranfparent Coloured Subflances, the Colouring 

 Matter does not rejieEi any light -y and when by in- 

 tercepting the light whici) was tranfmittcd, it is 

 hindered from paffing through fuch fubftances, 

 they do not vary from their former colour,* to 

 any other colour, but become entirely black. 



As 



• Optical writers generally ufe the word colour in an 

 equivocal fenfe : fomeiimes exprefTing thereby the primary 

 colours, as oppofed to whitenefs : at other times including 

 whitenefs alfo, I have, throughout this inquiry, ufed this 



word 



