Pemanent Colours of Opake Bodies, 159 



the rays of light. And indeed, fronn the ftatc 

 and extent of his refearches, it was not pofTible 

 that he could have attained to a clear infighc 

 into that part of Optics, as he was not furnifhed 

 with any regular feries of experiments, which 

 could be applied to the folution of its phceno- 

 mena. 



As the progrefs of Sir Ifaac Newton's difco- 

 veries did not extend beyond the limits of his 

 experiments, it may be fairly concluded, that, 

 without fuch fources of information, the moft 

 acute and penetrative underftandings muft fail 

 of fuccefs in phyfical inquiries. 



This great philofopher, however, in the few 

 paflages wherein he treats of Coloured Subftances, 

 conftantly avows his defedl of experiments. It 

 is probable that, by this candid acknowledg- 

 ment, he intended that the opinions which he 

 had exprefled, on this fubjeft, which are merely 

 conjedlural or founded on abftratt fpeculation, 

 might be diftinguilhed from thofe clear truths, 

 which he had deduced from his numerous and 

 accurate experiments, performed with Tranfpa- 

 rent Colourlefs Bodies. 



Thus, having mentioned fome of thofe fub- 

 flances, which tranfmit one fort of light and re- 

 flecT: another fort, he makes this remark : " If 

 *' thefe liquors or glaffes were fo thick and maffy, 

 " that no light could get through them, I quef- 



tion not but they would, like all other opake 



*^ bodies. 



tc 



