76 An Inquiry co7tcerning the 



sufficiently curious and interesting to merit the atten- 

 tion of those who take pleasure in, the cultivation of 

 experimental philosophy. 



Having found that gold or silver might be melted 

 by the heat (invisible to the sight) which exists in the 

 air, at the distance of more than an inch above the 

 point of the flame of a wax candle (see my Seventh 

 Essay, Part II., page 350*), I was curious to know 

 what effect this heat would produce on the oxides of 

 those metals. 



Experiment No. i. — Having evaporated to dryness 

 a solution of fine gold in nitro-muriatic acid, I dis- 

 solved the residuum in just as much distilled water as 

 was necessary in order that the solution (which was 

 of a beautiful yellow colour) might not be disposed to 

 crystallize ; and wetting the middle of a piece of white 

 taffeta ribbon, \\ inch wide and about 8 inches long, 

 in this solution, I held the ribbon (with both my hands) 

 stretched horizontally over the clear, bright flame of a 

 wax candle ; the under side of the ribbon being kept 

 at the distance of about \\ inch above the point of the 

 flame. The result of this experiment was very striking. 

 That part of the ribbon which was directly over the 

 point of the flame began almost immediately to emit 

 steam in dense clouds ; and in about 10 seconds, a circu- 

 lar spot about I of an inch in diameter having become 

 nearly dry, a spot of a very fine purple colour, approach- 

 ing to crimson, suddenly made its appearance in the 

 middle of it, and spreading rapidly on all sides became, 

 in one or two seconds more, nearly an inch in diameter. 



By moving the ribbon, so as to bring in their turns 

 all the parts of it which had been wetted with the solu- 



* See Vol. I., page 370. 



