24 Account of the Gold and Silver Mines of Hungary. 
tremely well luted. Nine marks are placed in each vessel, with 
about twice that weight or somewhat less of nitric acid of the 
specific gravity of 1:20, previously purified of any combined sul- 
phuric or muriatic acid it might contain, by dissolving in it a 
portion of perfectly pure silver. These retorts are placed in a 
sand-bath, with receivers properly fitted to collect any acid fumes 
which may pass over. The silver is in this process taken up by the 
nitric acid, forming a clear solution, which being decanted off, 
leaves as a residuum the gold, in the state of protoxide, having 
the appearance of a brown powder. This, when collected in a 
crucible and exposed to a low heat, assumes its yellow colour, 
but without metallic lustre; the particles adbering but slightly 
together. It being however perfectly pure, nothing further is 
necessary than to fuse and cast it into ingots. 
The transparent solution of silver in the nitric acid is now 
poured into retorts standing in the sand-bath, and, being gently 
heated, is distilled over into receivers in astate fit to be employed 
in fresh solutions, leaving the silver in a sponge-like metallic 
form chiefly at the bottom, but likewise adhering in a thin coat 
to the sides of the retort, without lustre, but beautifully white. 
Fresh quantities of the solution are then poured into the retorts, 
and the distillations repeated until they are nearly half full of 
dry nitrate of silver: a considerably greater heat is then applied, 
in order to decompose the metallic salt. The retorts are then 
broken, and their contents with the adhering pieces of glass and 
a portion of black flux run down in black-lead crucibles, and the 
silver cast into ingots. 
The laboratory is of great extent. Five or six banks of sand, 
for so they may well be called from their size, extend across the 
chamber, beneath which the fire is conducted in flues; and upon 
the whole extent, processes of solution and evaporation are 
constantly going on. Here are also all the furnaces and appa- 
ratus necessary for performing the several operations befere 
mentioned. 
Both gold and silver in their greatest degree of purity are 
found too soft for circulation in coin: before, therefore, they are 
made into money, the standard is reduced by the addition of 
alloy cither of silver or copper, to give the necessary degree of 
hardness and durability. In the inferior silver coins much more 
is added to increase their weight and dimensions, as well as for 
other sufficient and perhaps not less obvious reasons. In the 
Austrian pieces of twenty kreutzers there are only nine loths, 
thirteen grains of silver, to five loths six grains of copper. In 
the gold coins, however, the proportion of alloy is exceedingly 
small. A ducat weighing 53:85 grains contains only 0°56 
grain of copper, with 53°29 of gold; and according to the an- 
cient 
