pji PBEPABATIONS OF GO;tD. 255 



same precautions, acquired a slight yellow tinge, and at and jr^^tly a - 

 kngth furnished a.salt of the same colour, which had no y^''"* '-^^J 

 regular figure. • With this were mixed a few crystals of car- 

 bonate of potash perfectly colourless. The coloured salt, 

 being well drained, produced no very decisive effervescence 

 with muriatic acid, though the colourless crystals effer- 

 vesced with it briskly ; but its solution was not coloured. 

 The coloured crystals, when redissolved in water, yielded 

 a copious precipitate of metallic gold on the addition of 

 sulphate of iron. The mother-water of these crystals ef- 

 fervesced with muriatic acid, and afterward gave a precipi- 

 tate of metallic gold with sulphate of iron. 



These experiments seem to prove, that these crystals, as beinga triple . 



well as their niother-water, are composed of muriate of "^^^'^'^°' 



gold and pot- 

 gold and muriate of potash united together in the state of a ash. 



triple salt ; and that the carbonate of potash is only mixed 



wi^h them. 



Hence it appears very probable, that, if a solution of Perhaps this 

 gold, as nearly in the neutral state as possible^ were mixed ^^'^ "«* preoi- 

 with a sufficient quantity of muriate of potash, alkalis kalis : 

 would throw down no precipitate from this mixture. 



To prove this, I made the experiment above; but I ob- but the con- 

 tained a precipitate with carbonate of potash: thou^jh it isi^cturenat 



1111 o ir,- 1 1 /. confirmed by 



true much less abundant, ot a dinerent colour, and ot a experiment. 



different appearance, from that obtained vvith a solution of 

 pure gold. Its colour was yellow, and its form granular, 

 not flocculent like that of oxide of gold. 



An examination of this precipitate informed me, that it Precipitate. 

 was composed of muriate of gold, and muriate of potash 

 rendered little soluble by the presence of alkali in the li- 

 quor, from which it had been separated. 



One thing remarkable is, that, after having precipitated a OxideofgoUl 



solution of gold by means of an excess of saturated car- f^fo^'"^ ^^o'^'^ 



f I f r^ • • o • 1 t by an acid. 



bonate of potash, ii a sufficient quantity or acid to decom- 

 pose the alkaline salt be added to the filtered liquor, a few 

 flocks of oxide of gold will be separated; and afterward, 

 this liquor being filtered, if muriatic acid be added, it will 

 yield a fresh precipitate by the help of boiling; but the last 

 19 a triple salt, similar to that which has just been men- 

 tionedr 



I 



