MERCURY. 



litmus paper, but changes simp of violets 

 to green. Bicarbonate of potash throws down from 

 it a deep brick-red precipitate, from which metallic 

 mercury may be procured, by heating it in a tube. 

 Lime-water causes a deep yellow precipitate, verging 

 mi rt-d. Water of ammonia forms a white precipitate, 

 which becomes yellow on being heated. With sul- 

 phureled hydrogen and hydrosulphurets, a black, or 

 blackish-brown precipitate appears. Nitrate of 

 silver throws down the curdy precipitate characteris- 

 tic of muriatic acid ; and the proto-muriate often 

 gives a white precipitate. From six to twelve 

 grains were the mortal doses employed by Orfila, in 

 his experiments on dogs : they died in horrible con- 

 vulsions, generally in two hours ; but when with a 

 larger quantity, the whites of eight eggs were thrown 

 into the stomach, the animals soon recovered after 

 vomiting. The effect of this antidote is to convert 

 the corrosive sublimate into calomel. Sulphureted 

 hydrogen may also be employed along with emetics. 

 The proto chloride of mercury (mercurius dulcis, 

 or calomel), is usually formed from the deuto-chloride, 

 by triturating four parts of the latter with three of 

 quicksilver till the globules disappear, and subjecting 

 the mixture to a subliming heat. By levigating and 

 edulcorating with warm water the sublimed grayish- 

 white cake, the portion of soluble corrosive sublimate 

 which had escaped decomposition is removed. It 

 may also be made by adding solution of proto-nitrate 

 of mercury to solution of common salt ; the proto- 

 chloride, or calomel precipitates. The following is 

 the process used at Apothecaries' Hall, London: 

 Fifty pounds of mercury are boiled with seventy 

 pounds of sulphuric acid to dryness, in a cast-iron 

 vessel ; sixty-two pounds of the dry salt are tritur- 

 ated with forty pounds and a half of mercury until 

 the globules disappear, and thirty-four pounds of 

 common salt are then added. This mixture is sub- 

 mitted to heat in earthen vessels, and from ninety- 

 five to one hundred pounds of calomel are the result. 

 It is washed in large quantities of distilled water, 

 after having been ground to a fine and impalpable 

 powder. When proto-chloride of mercury is very 

 slowly sublimed, four-sided prisms, terminated by 

 prisms, are obtained. It is nearly tasteless and in- 

 soluble, and is purgative in doses of five or six grains. 

 Its specific gravity is 7*176. Exposure to air darkens 

 its surface. It is not so volatile as the deuto-chloride. 

 Nitric acid dissolves calomel, converting it into cor- 

 rosive sublimate. Proto-chloride of mercury is com- 

 posed of mercury 84-746, and chlorine 15-254. 

 There are two iodides of mercury ; the one yellow, 

 the other red ; both are fusible and volatile. The 

 yellow, or proliodide, contains one half less iodine 

 than the deutioclide ; the latter, when crystallized, is 

 a bright crimson. They are both decomposed by 

 concentrated sulphuric and nitric acids. The metal 

 is converted into an oxide, and iodine is disengaged. 

 They are likewise decomposed by oxygen, at a red 

 heat. 



Mercury, on account of its fluidity, readily com- 

 bines with most of the metals, to which it communi- 

 cates more or less of its fusibility. When these 

 metallic mixtures contain a sufficient quantity of 

 mercury to render them soft at a mean temperature, 

 they are called amalgams. It very readily combines 

 with gold, silver, lead, tin, bismuth, and zinc ; more 

 difficultly with copper, arsenic, and antimony ; and 

 scarcely at all with platina or iron. It does not 

 unite with nickel, manganese, or cobalt ; and its 

 action on tungsten and molybdena is not known. 

 Looking-glasses are covered on the back-side with 

 an amalgam of tin. (See Silvering.) The medicinal 

 uses of mercury have already been alluded to. The 

 amalgamation of Uie precious metals, water gilding, 



the making of vermilion, the silvering of looking- 

 glasses, the construction of barometers and thermo- 

 meters, are the principal uses to which this metal is 

 applied. Scarcely any substance is so liable to 

 adulteration as mercury, owing to its property of 

 dissolving completely some of the baser metals. 

 This union is so strong, that they even rise along 

 with it in vapour when distilled. Its impurity, how- 

 ever, can generally be detected by its dull aspect ; by 

 its tarnishing, and becoming covered with a coat of 

 oxide, on long exposure to the air ; by its adhesion 

 to the surface of glass ; and, when shaken with 

 water in a bottle, by the speedy formation of a black 

 powder. Lead and tin are frequent impurities, and 

 the mercury becomes capable of taking up more ot 

 these, if zinc or bismuth be previously added. In 

 order to discover lead, the mercury may be agitated 

 with a little water, in order to oxidize that metal : 

 pour off the water, and digest the mercury with a 

 little acetic acid ; this will dissolve the oxide of 

 lead, which will be indicated by a blackish precipi- 

 tate, with sulphureted water ; or to this acetic solu- 

 tion, add a little sulphate of soda, which will preci- 

 pitate a sulphate of lead, containing, when dry, 

 seventy per centum of metal. Bismuth is detected 

 by pouring a nitric solution, prepared without heat, 

 into distilled water ; a white precipitate will appear, 

 if this metal be present. Tin is manifested, in like 

 manner, by a weak solution of proto-muriate of gold, 

 which throws down a purple sediment ; and zinc, by 

 exposing the metal to heat. 



Ores of Mercury. The native mercury and the 

 sulpkuret are the only two ores explored for the 

 extraction of this metal. The first of these is found 

 in globules, disseminated through different rocks, 

 adhering to the sides of cavities and fissures in the 

 form of little drops, and rarely accumulated in basins 

 of considerable dimensions, so as to admit of being 

 dipped up in pails ; though it never occurs in suffi- 

 cient quantity to form the sole object of exploitation. 

 Occasionally it is found amalgamated with silver, 

 containing one third its weight of this metal ; in 

 this condition, it is rarely observed crystallized under 

 the form of the rhombic dodecahedron. The sul- 

 p/iuret is the common ore, which furnishes nearly all 

 the mercury of commerce. It occurs, crystallized, 

 in rhomboids, and six-sided prisms and tables ; colour 

 cochineal red ; lustre admantine and splendent ; 

 translucent; streak scarlet-red, shining; harder 

 than gypsum, sectile, and easily frangible ; specific 

 gravity, 6-7 to 8 - 2. It also occurs massive and 

 compact, and often blended with bituminous matter, 

 which communicates to it a liver-brown or black 

 colour, whence the name of hepatic cinnabar. This 

 ore is very rich, and affords, by analysis, eighty-four 

 or eighty-five per centum of mercury ; that which is 

 bituminous gives eighty-one per centum. The 

 muriate of mercury, or horn quicksilver, is so rare, 

 and presents itself in such small quantities in the 

 mines, as scarcely to receive the attention of the miner, 

 and it is sought after only by the mineralogist. It 

 occurs in incrustation, and rarely crystallized in 

 quadrangular prisms, terminated by pyramids. It is 

 translucent, with a lustre between adamantine and 

 vitreous, and is sectile. It consists of 76 oxide of 

 mercury, 16*4 muriatic acid, and 7'6 sulphuric acid. 

 The ores of mercury are more frequent in secondary 

 than in primitive rocks, and are found particularly 

 in sandstones, bituminous shales, and argillite, often 

 accompanied by organic remains. In general, mer- 

 cury is a metal which cannot be said to have a wide 

 distribution, and the mines which furnish it in quan- 

 tity are few. The principal are those of Idria, in 

 f the Austrian dominions, discovered in 1497, and 

 which chiefly afibrd a bituminous sulphuret of this 





