Oti^ the Chemical Propertlei attributed to Light. 45^ 



means of ether, I conceived it might be pofllble to perform that chemical procefs, in the 

 tmift ivay, by means of eflential oils ; and this conje£lure proved to be well founded. 



Experiment No. 14- Upon a quantity of a diluted aqueous folution of nitro-murlatc 

 of gold, in a fmall pear-like phial, about li- inch in diameter at its bulb, was poured a 

 fmal! quantity of etherial oil of turpentine, juft as much as was fuiBcient to cover the 

 aqueous folution to the height of \ of an inch ; and the phiuj, being well clofed with a 

 good cork, well fecured, was expofed one hour to the heat of boiling water in a fteam- 

 veflel. 



The gold was revived, appearing in the form of a fplendld pellicle, of a bright gold co- 

 lour, which floated on the furface of the aqueous liquid. The oil of turpentine, which, 

 at the beginning of the experiment, was as pale and colourlefs as pure water, had taken a 

 bright yellow hue ; and the aqueous fluid, on which it repofed, had entirely loll its yel- 

 low colour. 



On {baking the phial, its contents were intimately mixed ; but, on fufFering it to ftand 

 quiet, the oil of turpentine foon feparated from the aqueous liquid, retaining its bright 

 yellow hue, and leaving the aqueous liquid colourlefs. 



On (baking the phial, before it had been expofed to the heat, and mixing its contents, and 

 then fuffering it to ftand quiet, the oil of turpentine, on taking its place at the top of the 

 aqueous folution, was not found to have acquired any colour ; nor was the bright gold 

 colour of the folution found to be at all impaired. When liilphuric ether was ufed ir.- 

 ftead of the oil of turpentine, the effe£l: was in this refpe£l very different. 



To find out whether the oil of turpentine ufed in this experiment, and which had ac- 

 quired a deep yellow colour, had loft that property by which it efFeiled the redu(flion of 

 the metallic oxide, I now poured an additional quantity of the aqueous folution of the 

 oxide into the phial, and, Ihaking the phial, expofed it with its contents to the heat of 

 boiling water. 



After it had been expofed to this heat about two hours I examined it, and found, that 

 though a confiderable quantity of gold had been revived, yet the aqueous liquid ftill re- 

 tained a faint yellow colour. 



The oil of turpentine had acquired a deeper and richer gold colour, approaching to 

 orange. 



To the contents of the phial I now added about half as much diftilled water, and, 

 mixing the whole by fhaking, I expofed the phial again, during two hours, to the heat of 

 boiling water ; when the remainder of the oxide was reduced, and the aqueous liquid left 

 perfectly colourlefs. 



On repeating this experiment with oil of turpentine, and varying it, by ufmg a folution 

 of the oxide oiftlver (an aqueous folution of nitrate of filver,) inftead of that oi gold, the 

 refult was nearly the fame : the metal was revived, and the oil of turpentine acquired a 

 faint greenilh- yellow colour. 



I alfo revived the oxides of gold and of filver with oil of olives, by a fimilar procefs, with 

 the heat of boiling water. The oil of olives ufed in thefe experiments loft its tranfpa- 

 rency, and became deeply coloured : that ufed in the redu£lion of the oxide of filver 

 taking a very deep dirty brown colour, approaching to black ; and that employed in 

 reducing the oiide of gold being changed to a yellowifli-brown, with a purple hue. 



3 N 2 In 



