Robique t ow il romn . 117 



•willingly find this inodorous volatile oil, that they may mix it with 

 the more rare and dear essences. I shall terminate this note 

 by a final observation ; it is, that the analysis of the essence of 

 turpentine, published by M. Houton Labillardi^re, and that of 

 the essence of lemons of M. de Saussure, afford such unequal 

 results as to indicate a similar composition, and show that the 

 different odours which distinguish them belong to causes 

 which have little influence on their intimate nature. 



Art. XII. Facts relative to Gold, Extracted from a 

 Memoir read to the Institute, By M. Pelletier, 



Notwithstanding the different researches on gold, and its 

 combinations, which have been published, there still remain 

 many points to be elucidated, especially relative to the saline 

 compounds of this metal in their property of forming, at times, 

 colourless combinations with the acids and the alcalies. This 

 property has been observed several years ago by chemists, and 

 principally by M. Vauquelin, but the theory of the effect remains 

 unknown. M. Pelletier, who, conjointly with M. Duportat, had 

 published experiments on this subject, did not conceal the 

 vacuities which existed in his work ; and it is with the intention 

 of filling them up, that the new experiments have been under- 

 taken, of which the following is an account. 



M. Pelletier divides his memoir into several parts. The first 

 is devoted to the examination of the action of mineral acids on 

 the chloride of gold. 



It is known that the chloride of gold is capable of combining 

 with water, and forming a yellow hydrate, which, when heated, 

 becomes of a purple colour, from the evaporation of the water. 

 By the continued action of the heat, this purple powder becomes 

 of a lemon yellow colour, and M. Berzelius then considers it a 

 sub-chloride of gold. 



From this phien^menon it is easy to explain the action of acids 

 on the chloride of gold. The acids, such as the sulphuric, 

 nitric, and phosphoric, do not act, when cold, on this compound, 



