Page:The New International Encyclopædia 1st ed. v. 13.djvu/370

* MERCURY. 336 MERCURY. cury, producing about 1000 tons of metal an- nually. The mines of Terlingua have not been developed sulliciently to test their value. In foreign countries mercury is produced in Mexico, Spain, Italy, Austria, Russia, Australia, and China. The Spanish mines at Ahnad^n yield about one-third of the world's total jiroduction. In 1000 the production of the different countries was as follows: Austria. 550 metric tons: Italv, 220 tons: Mexico, 335 tons: Russia, 340 tons; Spain, nil tons; United States, 967 tons; total, 3523 metric tons. Mercury (symbol, Hg; atomic weight, 200.3) is a silver-white liquid metal that solidifies at — 40° C. ( — 40° F.), and, while slightly volatile at ordinary temperatures, boils at al)out 300° C. (048° F.). Its speeitie gravity at 0° C. (32° F.) is 13.59. Its principal uses are in the separation of gold and silver from their ores, in the manu- facture of vermilion, in medicine, in various chemical and physical operations, in tlie manu- facture of alloys, etc. It dissolves and possibly combines chemically with nearly all of the metal- lic elements to form alloys termed 'amalgams' (q.v. ). With oxygen it forms two oxides, of which the mercurous oxide is obtained by the action of caustic alkalies on mercurous salts, while the mercuric oxide ('red oxide of mer- eury.' or 'red precipitate') is fonned by pro- longed heating of mercuni' in air. The latter oxide is used in medicine and as an oxidizing agent in chemical operations. Corresponding to the two oxides, mercurv forms two series of com- pounds, which are known as mercurous and mercuric salts. Among these, one of the most important is the mercuric sulphide found native as cinnabar, and when prepared artificiallv is the red pigment known as vermilion (q.v.). The two chlorides are important commercial salts, and of these the mercurous chloride, or calomel (q.v.), occurs native. The mercuric chloride. or corrosirc sublinuitc. finds extensive use in medicine, and is extensively used for the preser- vation of skins and natural-history specimens. Jlercuric ammonium chloride is a white powder that is extensively used in medicine, under the name of uhite prccipilate, especially in the form of ointment. Metallic mercury and its salts are poisonous, and chronic mercurial poisoning is common anifing those who haliitually work with the metal. When taken internally, salivation, ulcers of the mucous membrane of the mouth. and ultimately paralysis, result. The usual antidotes arc albumen, milk, and Hour and water. See also llYr)Rionic .d upon n large scale. They are (1) extraction by heat- ing the ore in the air. and (2) extraction by heating the ore with lime or iron, air being ex- cluded. In both methods the chemical reactions take place at temperatures above the boiling point of mercury, so that the latter is separated in the gaseous form and has to be condensed. Heating the cinnabar in the air is a process per- formed in shaft, reverberatory. or miifllc fur- naces, and is preferred to methods using lime or iron, inasnuich as it is more economical and less dangerous to the workmen, whose health should be considered, since mercurial vapors arc exceedingly injurious. The leading objection to this method is the dilution of the mercurial vapors by sulphur dioxide, o.x,ygen, and nitrogen, especiall,v where shaft and reverberatory fur- naces are employed, b,v the products of combus- tion. For these reasons it is rallier dillienlt to condense the mercur,v, and therefore there are losses of the metal tlirough incomplete condensa- tion. On the other hand, where the mercury is extracted by heating the cinnabar with lime or iron, retorts are used in which the crushed ore is treated in small (|uautities. Concentrated mer- curial vapors are obtained from these retorts, and then condensed so that with a high grade of ore the output is somewhat greater than by the, first process. But as there is a much greater expense of labor and fuel, and as the process is unheallhful for the workmen, on account of the mercurial vapors in cmniying retorts; the process is less frequenth' employed. The extraction of mercury in the air consists in heating cinnabar with an excess of air to a high temperature. The heating is usually accom- plished in shaft or reverberatory furnaces, from ' which the gases pass into the condensers, con- '} sisting of a series of tubes and chambers, and are there cooled until the mercurial gases condense into metallic mercury, while the other gases es- cape. The process requires great care to prevent the loss of mercury and danger to the workmen, and in the Ijest operated plants the loss of mer- cury is at present not more than 8 per cent, of the metal in the ore. while every attempt is made to draw otV the mercurial gases by fans and other apparatus, and so to keep them confined that thc,y will not be inhaled by the workmen. Mercur.y is transported in wroughtiron flasks closed by a screw stopper and holding about 76 pounds of metal. Sheepskin bags are also used for this purpose. Consult: Schables. Ihindhook of Metallunj!/ (Xew York, 1898) ; Eggleston, }[rt<ilhirpii of Silrcr. (Sold, and Mercury (New York. 1890). MERCURY, Medicinal Uses of. The twenty; one olliiial |)roparations of hydrargyrum, or mer- cury, may be class! fieil as follows: (1) Prepara- tions of mercuri/. including mercury with chalk, blue mass, mercurial ointment, and two plasters of mercury: (2) the chlorides of niercurii and their preparations, including calomel, corrosive sublimate, and others; (3) the oxides and their preparations, including the red precipitate and others: (4) the iodides and their prcparatioM, including the red iodide, the ,yellow iodide, and others; (5) acid combinations and their prepara- tions, including the .solution of mercuric nitrate and others: (I!) cjianide of mcrenri/: and (7) the triturations. Resides the oflicial ])rcpara- tions. the following unoliicial jircparations are well known: Yellow .sidution of mercury ('yellow wash"), black lotion of mercury ("black wash' I. and red ointment of mercuric nitrate Cljrown citrine ointment') . Mercury is purgative, alterative, and tonic, and jironioles the flow of bile. Some of its prepara- tions are corrosive, some are caustic, some are poisonois. In small quantities .some of the mer- curial.; are tonic, while in large quantities they cause 'poverty of the blood.' ilitninishing the number of the reil corpuscles, reducing nutrition, and impairing digestion, finally causing waste of tissue. Long-continued exhibition of mcrcuiy causes a cachectic condition termed hydrargyriafc