214, ^^- T>slaval on the Caufe of the 



Liquors, impregnated with phlogifton (No. 

 6^y^c.) tranfmit coloured lisht, but do not re- 

 flcd any colours. Nor do the giaflTes which de- 

 rive their colours from inflammable, or metallic 

 matters, appear coloured by refledlion, but by 

 tranfmifllon only. 



From hence it is evident, that phlogiftic, or 

 metallic matters, when united with earths, do 

 not refled the coloured light : but are tranfpa- 

 rent coloured media, which tranfmit the light 

 refledted by the particles of the white earths. 



Metals, when in their entire metallic ftatc, are 

 endued with a ftrong refleflive power. All the 

 metals, except gold and copper, aft equally 

 upon all the rays of light, from which their white- 

 liefs arifes. 



Gold exhibits a white light, which is tinged 

 -with yellozv, I have ufed this exprefTion, becaufc 

 it appears, from experiment, that gold refleds a 

 •white light, and that its yellow colour is a tinge, 

 •which is fuperadded to its whitenefs. The ex- 

 periment is thus fet forth by Sir Ifaac Newton.* 

 ** Gold in this light, (that is, a beam of white 

 *' light) appears of the fame yellow colour as in 

 ** day light, but by intercepting at the lens a 

 " due quantity of the yellow making rays, it 

 " will appear white like filver, as 1 have tried, 

 *' which fhews that its yellownefs arifes from the 



• Newton. Opt. L. I. Part K. Prop. XI. Prob VI. 



** exccft 



