Part 9 (2/2)

The marine acid seizes upon isticated, the precipitate is _corrosive sublimate_; but with common marine acid, it is called _caloenerallyequal parts ofthe whole to a moderate heat; when the corrosive sublilass vessel in which the process is made

Mercury combines readily with sulphur by trituration, and with it forms a black powder called _Ethiops mineral_ A more intimate combination of mercury and sulphur is made by means of fire This is called _cinnabar_, about one third of which is sulphur Vermillion is cinnabar reduced to powder

Mercury readily unites with oil, and with it forms a deep black or blue compound, used in medicine

It readily combines with most of the metals, and when it is used in a sufficient quantity to aold, silver, lead, tin, bislasses are covered on the back with an aam of mercury and tin

When mercury is united with lead or other itation in pure air converts the iether with much of the mercury, in the form of a black powder

Heat recovers the pure air, and thethe calx of the impure metal

Much mercury is found native in a slaty kind of earth, or in reatest quantity is found combined with sulphur in _native cinnabar_

LECTURE XXIV

_Of Lead_

Lead is a reat tenacity, but very considerable specific gravity, being heavier than silver Itbefore it is red hot, and is then calcined, if it be in contact with respirable air When boiling it eranulated by being poured into a wooden box, and agitated

During congelation it is brittle, so that the parts will separate by the stroke of a hammer; and by this means the forress of calcination it first becorey powder, then yellohen it is called _ pure air, it becoreater degree of heat it beco parted with its pure air If the heat be too great, and applied rapidly, it becoe_; and with lass_, which readily unites with redient in theit its peculiar density and refractive power

Though lead soon tarnishes, the imperfect calx thus made does not separate from the rest of the metal, and therefore protects it from any farther action of the air, by whichof houses, and other similar purposes All acids act upon lead, and form with it different saline substances _White-lead_ consists of its union with vinegar and pure air Also dissolved in vinegar, and crystallized, it becoar of lead_, which, like all the other preparations of this metal, is a deadly poison

Oils dissolve the calces of lead, which, by this means, is the basis of paints, plaisters, &c

By e deco with the , and by this means the fossil alkali is separated

Lead unites with h not with iron Two parts of lead and one of tin make a _solder_, which melts with less heat than either of the ht parts of bismuth, five of lead, and three of tin,water

This metal will be dissolved by water if it contain any salineof it occasions a peculiar kind of cholic

Lead is soenerally minerally mineralized with sulphur or arsenic, and often mixed with a small quantity of silver

_Of Copper_

Copper is a metal of a reddish or brownish colour, considerably sonorous, and very malleable