Part 8 (2/2)

Metallizable earths, coiston, ravity, their opacity, shi+ning appearance, and fusibility

All the proper metals are _malleable_, and those which are not so are called _seain are subdivided into the _perfect_ and _iold_, _silver_, and _platina_, suffer no change by fusion, or the longest continued heat: whereas heat calcines or dissipates the phlogiston of the imperfect metals, which are _mercury_, _lead_, _copper_, _iron_, and _tin_, so that they return to the state of earth; and this earth is always heavier than thereceived an addition of weight fro exposed to heat in contact with substances containing phlogiston, again become metals, and are then said to be _revived_

The seulus of _arsenic_, of _cobalt_, of _antianese_, of _wolfram_, and of _molybdena_

All metallic substances are crystallizable, and each in a peculiar for a hole in the botto out the stopper, when theto lose its fluidity

Some of the metals will not unite to others when hot, and others of them will; and such as will unite with others are called _solders_ Thus tin is a solder for lead, and brass, gold, or silver, for iron

Ores are never found in regular strata, like the different kinds of earth; but in places which have for in all directions, with respect to the regular strata, and commonly called _veins_

Many of the ores in their natural state are said to be _mineralized_ with arsenic or sulphur, those substances being intimately united with the metallic earths

In order to convert the ores into metals, some of them are first reduced to powder, to wash out the earthy or saline particles They are then kept in a red heat, which the work_, in order to drive away the arsenic, or sulphur, which are volatile; and in the last place they are fused in contact with charcoal, or other substances containing phlogiston; and to promote the fusion, lime-stone is frequently mixed with them When the operation is colass, or _scoria_, which lies on the surface, whereas the metal is found at the bottom

To discover the quantity of _

When ravity, fusibility, and other properties are changed, and in such a manner as could not be discovered from the properties of the constituent parts

_Of Gold_

Gold is the heaviest of all metallic bodies except platina It appears yellow or reddish by reflected light, but green or blue by transh gold undergoes no change in a co lens, it may, in part, at least, be calcined by the electric shock

Gold has the greatest _ductility_, and in wires of equal diareatest _tenacity_, of all the rain of itless than a 200,000th part of an inch thick; and when it is old upon it may not be old leaf

Thisprecipitated by a volatile alkali, makes a powder called _auruold, and explodes with great violence in a heat so water

Tin precipitates gold in the form of a purple powder, called the _powder of Cassius_, frolassy coating which is given to metals by heat

Gold unites with most of the metals, especially with , the ailded, and the old attached to the surface

Goldinstruold from the imperfect metals, such as copper, &c it isheat, which calcines the lead, and with it the iold pure This process is called _cupellation_, fro perforold is mixed with silver, three parts more of silver are put to it, and then the silver is dissolved by nitrous acid, leaving the gold pure This process is called _quartation_, fro one fourth part of the enerally estiold into twenty-four parts, called _carats_ The phrase twenty-three carats fine means that the mass contains twenty-three parts out of twenty-four of pure gold, the reold may in some measure be discovered by the colour it leaves upon a _touch-stone_, or fine-grained basaltes

Gold is generally found nearly pure, but h stones