HISTORY OF GOLD. 241 



It occurred to me to plunge the steel into water the mo*, 

 ment I had traced the figures, and afterwards to dry it ; pre* 

 suming I should thus diminish the inconveniences arising from 

 the muriate of iron ; but the figures did not acquire from this 

 more adhesion, or more lustre. The palm of the hand appli- 

 ed gently to polish them, rubbed them off immediately. 



It was to as little purpose that I dried the steel, after it wa* 

 gilded and washed, with a heat sufficient to burn the hand. 

 The gold indeed was thus rendered more firmly adherent', but 

 friction would not give it more lustre, because, however the 

 ether may be loaded with it, it never deposits enough on the 

 figures to cover the blackness of the metal, and to give that 

 continuity of parts, that consistence, and that reflection of 

 light on which the brilliancy of gold depends. Finally, this 

 gilding, as it is now before me on the plates with which I made 

 my experiments, is not even equal to what may be produced 

 by a solution of sulphate of copper. If such were the results 

 of an ether loaded with gold, and from which I might have 

 promised myself some success, what is to be expected from an 

 auriferous ether prepared according to the common receipts ? 



Various precipitates of Gold. 



Gold precipitated by sulpurated hydrogen, washed and dri- Gold precipi- 

 ed, is nothing but a mixture of sulphur and pure gold. Heat- p^^i^iated ^hy- 

 ing it in a retort is sufficient to separate the metal from the drogen : 

 sulphur. C«'nsequently there is neither a sulphuret nor a hy- 

 drosulphuret of gold. 



The sulphureous acid precipitates it pure. The gold is in ^by sulphure- 

 such a state of division, that I conceived at first it might be ^^'^ *°''* •" 

 employed for painting on enamel, or for gilding ; but the me- 

 tallic particles were quickly susceptible of an attraction, that 

 collected them together, consolidated them, and made them 

 assume the consistency of a tenacious, though spongy sub- 

 stance. In this state nothing more is to be done with thera. 



Of the precipitation of Gold by the sulphate of Iron* 

 With the solution of this salt we succeed much better, and —by suipfeate 

 the result is a fine powder of a purple-red colour, the tint of *^*""*^*^ 

 which, however, is nothing like the purple of Cassius. Being 

 washed in acidulated water to free it from iron, it is to be kept 

 Vol. XIV.— July, 1805. li uuder 



