SILVER. 177 
as to indent both the anvil and the hammer. Four or 
five grains are as much of this powder as ought to be 
used for such experiments. Its force is much greater 
than that of gunpowder, but does not extend so far. 
Hence it is a substance which might be rendered of 
great use in the blasting of rocks. 
Corrosive sublimate is an extremely poisonous prepa- 
ration from mercury. Among other uses, it is employed 
by dyers as a mordant to fix their colours. From cer- 
tain proportions of corrosive sublimate rubbed together, 
until they are perfectly incorporated, is formed calo- 
mel; a salt which, of late years, has been extensively 
and most usefully employed in medicine. 
A valuable red colour or pigment called vermilion, 
or artificial cinnabar, which was as well known to the 
ancients as it is to the moderns, is usually formed of 
three parts of mercury and one of sulphur, melted to- 
gether, heated to redness, and then sublimated out cf 
contact of the air. The manufacture of vermilion was 
long kept a secret by the Dutch ; and it is stated that, 
before the late war, nearly 50,000 pounds weight of it 
were annually made, in three furnaces, by four work- 
men, near Amsterdam. Native cinnabar is sometimes 
used for the same purpose ; but the artificial kind is 
preferred on account of the purity and brightness of its 
colour. 
229. SILVER is a white, brilliant, sonorous, and ductile 
metal, somewhat more than ten times heavier than water. 
It is found in different states. Of these the principal is 
denominated native silver, from its being nearly in a state of 
purity. Native silver sometimes occurs in small lumps, some- 
times in a crystallized form, and sometimes in leaves, threads, or. 
wire. In many instances the latter are so connected zcith each 
other as to resemble the branches of trees, in which case the ore. 
is called dendritic. There are also several ores of silver, in 
which this metal is combined with lead, antimony, arsenic^ 
sulphur, and other substances. 
The silver that is. produced from the mines of Potosi, 
in South America, is of the dendritic kind; and is con- 
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