20 On the apparent Converjlon 



afterwards by filver from the muriatic acid. It cannot here 

 be difcovered how gold could be conveyed to the filver by 

 the folvcnt and precipitant employed ; and therefore, to ap- 

 pearance, a part of the filver is a6lually converted into gold. 

 Enlightened chemifts, however, will fcarcely believe in this 

 tranfmutation, and will rather fufpeft fonie deceptio7i. I 

 confcfs that I do not myfclf believe in it, and I explain the 

 appearance of gold from the revived horn filver in the fol- 

 lowing manner : — ^Notwithftanding the great difference be- 

 tween gold and filver, fome filver is almofi: always prefent in 

 pure gold ; and a little gold is in like manner almofi; always 

 prtfcnt in pure filver (in thofe commonly called pure). The 

 cafe is the fame in thefe metals when worked, particularly 

 in ccnns, even where they are not alloyed one with the other. 

 In all the ducats I have hitherto tried, even in thofe of 

 Holland, I found, on diflTolving them in aqua regia, a little 

 filver depofited in the form of horn filver. In all French 

 crowns, even in the fine Harz florins which are perfeftly free 

 from copper, I found a little gold, which, when they were 

 diflclved in the nitrous acid, was thrown down in a dark 

 coloured precipitate, which could not proceed from the al- 

 loying. Dutch ducats, for example, are not, as far as I 

 know, alloved with filver; and no one certainly will believe 

 that the gold found in the Harz florins and French crowns 

 was purpofely added to them. The metal of thefe coins has 

 from nature a fmall portion of foreign metals ; the gold a 

 little filver, and the filver a little gold, as long as it is not 

 purified by quartation — or the gpld by antimony. If a folu- 

 tion therefore be formed of fuch filver, the gold remains un- 

 diHolvcd, and graduidlv depofits itfelf at the bottom as a fine- 

 black powder. 



It may be readily comprehended, that every chemift, unlefa 

 he has very little experience in fuch proceffes, when he 

 wifhes to precipitate filver as horn filver, will firft pour off 

 nud filter the clear folution of filver and copper from the 

 l)l?x-k gold powder, before he adds the muriat of foda. On 



a hafiv 



