ON PREPARATIONS OF GOLD. 



953 



atoms of muriate, notwithstanding the repeated washings it 

 had undergone. 



But if potash and its carbonate precipitate in the state of Why Isnotihe 

 oxide part of the gold dissolved in muriatic acid, why do Precipitate ho* 



• •■ I ^ / mogeneou?? 



they not precipitate the whole ? and what becomes of the 



part left in the liquid, and in what state is it there ? 



This we shall examine by and by : at present let us de- 

 scribe the properties of oxide of gold. 



The oxide of gold, prepared in the manner above-men- Properties of 

 lioned, has very sensibly a styptic metallic taste, which ex- '^^f/l^***' '^f 

 cites the secretion of saliva copiously, and for a long time, tained. 

 If it be diluted with water, and blotting paper, or any other 

 porous combustible substance, be impregnated with it, it 

 causes them to burn with scintillation, as gunpowder would 

 do. A decigramme []'544 gr.] of this oxide, in a state of 

 minute division, and shaken for some time in 60 gr. [926*7 

 grs] of distilled water, was not dissolved, at least entirely; the 

 filtered liquor however, though perfectly clear and colourless, 

 afforded with sulphate of iron a pretty copious blneish pre- 

 cipitate, which was metallic gold. This proves, that a so- 

 lution in water had taken place: but as this solution might 

 have arisen from some portions of salt remaining with the 

 oxide for want of sufficient washing, I poured fresh por- 

 tions of water repeatedly on the undissolved portion, and by 

 the same means as above-mentioned found gold dissolved in 

 them all ; though it is true the proportion gradually dimi- 

 nished as the washings were more numerous. Though I did 

 not dissolve the decigramme of this substance entirely, ap- 

 parently because the latter portions were not sufficiently 

 divided ; I have no doubt from the little that remained, that 

 I should at length have dissolved the whole, if I had con- 

 tinued my trials. 



What seems to prove it is, that the last washings, which 

 still gave evident signs of the presence of gold, when tested 

 with sulphate of iron, afforded no appearance of the pre- 

 sence of muriatic acid on adding nitrate of silver. 



From these experiments we may prebume, that potash, Alkalis pro- 

 soda, and their carbonates, precipitate gold from its solu- ^^'P^^^fSoW**^ 



. . „.,.,/. . . an oxide, 



tion \n the state of oxide ; or that, at least, if any muriatic 



acid remain In the precipitate, it must be an infinitely 



small 



