52 ESSAYS AND OBSERVATIONS 



from the compounded colour of thofe rayS 

 which they refled j their colour being deno- 

 tninated by the fpecies of thofe primitive rays 

 which they refled: in greateft plenty : but 

 this part of the Newtonian dodtrine will re- 

 ceive further confirmation by examining the 

 different colours which the farne body 

 affumes when illuminated by different lights ;. 

 and which may be called, in difi:in<3:ion 

 from the former, their extraordinary colours. 

 i34i Bodies of all the principal colours, 

 *Diz. red, yellow, green and blue, are very 

 little altered vvhen feen by the light of burning 

 fpirits : but, if falts be continually mixed 

 with them during the burning, different 

 changes enfue. 



25. When fal ammcn. potafh or alum 

 are infufed, the colour of red bodies appears 

 fomewhat faded and dirty : green and blue 

 appear much the fame as in candle-light ; 

 both being faint and hardly diflinguifliible : 

 white and yellow are fcarcely at all affedled. 



26. When nitre or fea-falt are plentifully 

 mixed with the burning fpirits, and the 

 whole is ftirred about brifkly ; the brighteft 

 red bodies, feen by the light then emitted, 

 are reduced to a dirty tawny brown, that 



feenls 



