i8 On the apparent Converjion 



to the weight. The blue, prepared in this manner, is poured- 

 into oblong fquare iron moulds; and the cakes, when 

 formed, are placed upon fir boards on an airy floor in order 

 to dry, after which they are packed up for fale. 



IV. On the apparent Converfion of Silver into Gold. Bjf 

 Profejfor Hildebrant, of Erlangen^. 



JL HOUGH gold and filver have this common property, 

 that they fhew little affinity for oxygen, and their calces can 

 therefore be revived merely by ignition ; their difference in 

 other refpefts is fo great, that fcarcely any two metals can 

 be more unlike. Not only is their colour totally different, 

 and the fpecific gravity of gold far greater than that of filver, 

 but filver, in the dry way, forms a perfect union with ful- 

 phur ; and in the wet way, with the fulphuric and nitrous 

 acids ; whereas gold has no affinity for thefe fubflances. 



If the tranfmutation of metals were therefore pofTible, the 

 converfion of filver into gold would be very improbable. 

 We muff, however, confider nothing impoflible in nature, 

 the impoflSbility of which cannot be demonflrated a priori. 

 Each century, and, in the prefent a6live age, every fhort 

 period of a century, difcovers new phenomena, fome of which 

 are of fuch a nature that they would be confidered as im- 

 poffible, were not their reality fully confirmed by experience. 

 I entertain no dread then of being ridiculed by the un- 

 prejudiced philofopher, if I call the attention of chemifts to 

 a phenomenon in which filver appears to be converted into 

 gold. It is a well known procefs, which I repeat in every 

 courfe of my Lectures, to diffolve filver that contains copper 

 in pure nitrous acid, to precipitate the pure filver by common 

 fait (muriat of foda), in the form of horn filver (muriat of 

 ijlver), and thea to feparate the filver from the latter by 

 ftifion with mineral alkali. An experienced chemifi; Jtf- 



* From Al^cmeine's Journal da ChjmU, by A. N. Schercr, 1799. 



furcd 



