Oft ihe Chemical Properiks aiirihutedto L'tghi. '401 



lution (which was of a beautiful yellow colour) might not be difpofed to cryftallize ; and, 

 wetting the middle of a piece of white taffeta riband, i^ inch wide, and about eight inches 

 long, in this folution, I held the riband, with both my hands, ftretched horizontally over 

 the clear bright flame of a wax candle ; the under fide of the riband being kept at the dif- 

 tance of about i| inch above the point of the flame. The refult of this experiment was 

 very ftrilcing. That part of the riband which was directly over the point of the flame, be- 

 gan almoft immediately to emit fteam in denfe clouds j and, in about 10 feconds, a circular 

 fpot, about i of an inch in diameter, having become nearly dry, a fpot of a very fine pur- 

 ple colour, approaching to crimfon, fuddeniy made its appearance in the middle of it, and, 

 fpreading rapidly on all fides, became, in one or two feconds more, nearly an inch in dia- 

 meter. 



By moving the riband, fo as to bring, in their turns, all the parts of it which had been 

 wetted with the folution to be expt)fed to the aftion of the current of hot vapour that arofe 

 from the burning candle, all thofe parts which had been fo wetted, were tinged with the 

 fame beautiful purple colour. 



This colour, which was uncommonly brilliant, pafled quite through the riband, and I 

 found the ftainto be perfe£lly indelible. 1 endeavoured to walh it out ; but nothing 1 ap- 

 plied to it, and among other things I tried fuper- oxygenated marine acid, appeared in the 

 fmalleft degree to diminifh its luftre. The hue was not uniform, but varied from a light 

 crimfon to a very deep purple, approaching to a reddifli brown. 



I fearched, but in vain, for traces of revived gold, in its reguline form and colour ; but, 

 though I could not perceive that the riband was gilded, it had all the appearance of being 

 covered with a thin coating of the mod beautiful purple enamel, which, in the fun, had % 

 degree of brilliancy that was fometimes quite dazzling. 



Experiment No. 2. A piece of the riband which had been wetted with the aqueous 

 folution of the oxide, was carefully dried in a dark clofet, and was then expofed, dry, 

 over the flame of a burning wax candle. The part of the riband which had been wetted 

 with the folution (and which on drying had acquired a faint yellow colour) was tinged of 

 the fame bright purple colour as was produced in the lalt-mentioned experiment, when the 

 riband was expofed wet to the adlion of the heat*. 



. Experiment No. 3. A piece of the riband which had been wetted with the folution, 

 and dried in the dark, was now wetted with diftilled water, and expofed wet to the 

 a£lion of the afcending current of hot vapour which arofe from the burning candle : the 

 purple flain was produced as before, which extended as far as the riband had been wetted 

 with the folution, but no farther. 



I afterwards varied this experiment in feveral ways, fometimes ufing paper, fome- 

 times fine linen, and fometimes fine cotton cloths, inllead of the filk riband ; but nearly the 

 fame tinge was produced, whatever the fubftance was that was made to imbibe the aqueous 

 folution of the metallic oxide. 



Similar experiments, and with fimilar refults, were likewife made with pieces of riband, 



• We ftall hereafter find reafon to conclude, that the fuccefs of this experiment, or the appearance of the- ■ 

 purple tinge, was owing to the watery vapour which exiftcd in the hot current that afccndcd from tlxe fiame uf 

 the candle, R. 



fine 



