34 ESSAYS Anp OBSERVATIONS 
DB hoa Bom ee 
On the Change which coloured Bodies under- 
go in different Lights. 
23, S1r Ifaac Newton has abundantly 
proved, by a variety of arguments, that. 
the ordinary colours of natural bodies a- 
rife folely from the compounded colour of 
thofe rays which they reflect; their colour 
being denominated by the fpecies of thofe 
primitive rays which they reflect in great- 
eft plenty: But this part of the Newtonian 
doétrine will receive further confirmation 
by examining the different colours which © 
the fame body affumes when illuminated 
by different lights; and which may be 
called, in diftinétion from the former, 
their extraordinary colours. 
24. Bop1ks of all the principal colours, 
viz. red, yellow, green and blue, are very 
little altered when feen by the light of 
burning {pirits: But, if falts becontinual- 
ly 
