Jgj:^ ON PPKPARATIONS OF SOLD. 



The examination of this liqi|i4 I deft^rred, till another 

 time, to attend to the red precipitate iormed by the carbon- 

 ate of potash in the solution of gold. 



Tisc ;)rerii'-.- I began by wash in f^ this substance with boiling water, 



lAte examined. , , . ^ , , ,. , . ,i , r 



^ taknig care to keep each ot my washings separate, that I 



might more easily satisfy myself when it no longer contained 

 any thing soluble; but though 1 thus used a very large 

 quantity of water in proportion to its bulk,l was never able 

 to exhaust it; and it appeared to rae, that the last washings 

 SHightly salu- contained nearly as much gold as the firrft. Henc^I was led 

 We in vrater. ^o suspect, that the precipitate was slightly soluble in v.ater, 

 and that, by continuing to wash it, I should perhaps cause 

 Dried. it to disappear entirely. In consequence I ceased washing 



the precipitate, and dried it slowly. It greatly diminished 

 jn bulk, which proved, that it contained a large quantity of 

 Its colour. water. Its colour became a great deal deeper, and resem- 

 bled that of dried blood ; but v,<hen powdered it was of an 

 0«W tvro orange yellow. 7-643 gram. [118 grs] of fine gold, precipi- 

 ihifdsofthe pitated as mentioned above, furnished only 5*414 gr. 

 g>W precipi- j^gg .^ g^^-j ^^ j.^^ matter : whence it follpws, that 2'229 gr. 

 [34*3 grs] of gold at least, or a little less than a third, re- 

 mained in the mother-waters, and in the washings. 

 "No excess of Though I employed an excess of carbonate of potash to 

 carbonate m It precipitate the solution of gold, the red matter I obtained 

 did not contain any sensible quantity of this salt: for after 

 it was dried, it dissolved entirely in muriatic acid without 

 producing the least eiFerVescence; which proves, that it had 

 been entirely divested of carbonate by the washings, and 

 that the precipitate it formed retained no carbonic acid. 

 But it reia'ncd But it was not the same with respect to muriatic acid ; for 

 <ome murntic jj_ ^^gg necessary to employ repeated portions of nitric acid, 

 as will be seen belovv, to deprive the precipitate completely 

 of the muriatic: after this the nitric solution no longer af- 

 forded a •precipitate with the nitrate of silver. 

 PrebaWy an The presence of muriatic acid in the first solutions of this 

 oxiHe of gold jjjatter in nitric acid led me to suspect, that it was in the 



•with a little . r ^ ^ ^ 1 n-ii i 



muriate, state ot muriate or gold with excess ot oxide; but as the 



latter contained no more of this acid, it appeared to me 

 more probable, that it is pimply an oxide ret^iining a few 



atoms 



