the Nature oj fotne Mineral Subjlances. 615 
Silver, in its metallic ftate, is not foluble in diftilled 
vinegar. 
, EXPERIMENT VIII. 
Two drams of the pearl-coloured horn filver, treated 
with the like quantity of fixed alkaly as in the fir If expe- 
riment, produced fifty-one grains of neutral fait, com- 
pofed of flat cubic cryftals of regenerated lea-falt, with a 
mixture of brown cryftals of tartar of vitriol ; this laft, 
in appearance, is about a fourth or more of the firft. 
The filver here remaining had the fame appearance as 
that of the firft experiment; it alfo gave marks of its 
containing iron, but not near fo great a quantity as that 
of the feventh experiment. 
EXPERIMENT IX. 
The brittlenefs and colour of the black horn filver 
made me at firft doubt of its being horn filver; and I 
thought, that, if it contained any, it muft be mixed with 
fome other mineral fubft ance. Volatile alkalies having the 
property of diflolving all combinations of filver with 
acids, I availed myfelf of that well-known property on 
this occafion. I took, therefore, feven drams of the black 
horn filver, and digefted it at three different times with 
a large portion of volatile fpirit of hart’s-horn ; this fpirit 
I preferred to that of fal ammoniac , as I knew it to be 
free from acid of fait. The three folutions were mixed, 
filtered, and flowly evaporated to drynefs, and produced 
two drams and two fcruples of a dark flate-coloured horn 
filver. 
