MINERAL ACID. 536 MINERALOGY. MINERAL ACID (in .Modiuinc). An acid not of auimal or vegetable origin. The ordinary uiinoral acids are sulphuric (oil of vitriol), nitric (aqmi fortis), hydrochloric (muriatic), uitrohydrochloric, and phosphoric. In their medicinal action they have many properties in common. The strong acids are cscharotic, abstracting the waters of the tissues, combining with the albumin and other bases, and destroying the protoplasm. They are very diirusible. .Sulphuric and phosphoric acid have a strong affinity for - water, completely decomjiosing tissues to which they are applied; they are therefore powerfully escharotic. Sulphuric acid makes a black eschar, while nitric and hydrochloric acid turn the tis- sues yellow. These acids diluted produce a peculiar taste in the mouth and a sensation of roughness on the teeth. They stimulate the (low of saliva from the parotid and submaxillary glands. They promote the alkaline secretions of the intestines and of glandular organs (bile, etc.), but check the secretions of acid fluids, as the gastric juice. Given before meals, in small do.ses, they relieve undue acidity of the stomach by checking the production of the acid gastric juice. At first they aid digestion, being helpful to the action of pepsin, but if continued they impair digestion by lessening the production of the gastric juice. They check fermentation and constipate the bowels, except nitric acid, which relaxes them. They are all astringent to the tissues, hydro- chloric being the weakest and sulphuric the strongest in this respect. Antidotes for poisoning by these acids are: alkalies, such as bicarbonate of soda, lime water, or plaster from a wall mixed with water to neutralize the acid; oil, all)umin. and milk to protect the nuicous membranes. For stimulants, opii'.m and anunonia (intravenously) may be used to counteract the resulting depression of the vital powers. -Ml these mineral aeids, if well diluted, are useful in fevers, especially in typhoid. Hydro- chloric is here preferable. Nitric is the acid gen- erally preferred as a caustic, its action being elfectual and superlicial ; it may be applied un- diluted to i)hagedenic ulcers and sloughs, warty growths, an<l indolent .sores. Dilute nitric and nitrohydrochloric acids are used internally in oxaluria and lith.-emia. intermittent and remit- tent fevers. and aphonia of sin'jers. and in chronic hepatic disorders due to malaria. Sulphuric acid, dilute, is appropriate in cases of hemor- rhage, diarrha>a, colliiiuative sweating, and as a pro|)hylactic against Iiad-poisonin<_'; it is used also as an acid drink in fevers and before meals in acidity of the stomaih. Phosphoric acid is considered of special value in tissue waste, and it is thought to diminish the growth of osseous tumors, and to dissolve phosphatie deposits. All these acids act injuriously on the teeth, by at- tackins; the enamel. They should always be ad- ministered largely diluted, taken through a straw or glass tul)e; and the mouth should be thoriiu;,'bly rinsed at once with an alkaline wash. See XlTRIC ACMl; IIyI>I!0(I1I.()UI(' .(II), MINERAL COLORS. . term applied to a number of inor^'anic Mibstances used in the manu- facture of paints. The principal mineral colors inehule the following: iiliilr Innl. consisting chiefly of lead earbonatc; zinc white, or oxide of zinc; antimony iihilc, or oxide of antimony; fixed white, or barium sulphate; minerul irltite, or calcium sulphate; chiiia clay, or aluminum silicate; whiting, or calcium carbonate; native or artificial yellow ochres, i.e. earths colored by iron oxide; mussicut, or oxiile of lead; siron- tiun yellow, or chromate of strontium; the chro- mates of cadmium, mercury, and barium; min- eral yellow, or o.xychloride of lead; Xaples yel- low, or antimonate of lead; orpimeni, or sulphide of arsenic; rouge, or red oxide of iron; vermilion and cinnabar, or sulphide of mercury ; Derby red, or basic cliromate of lead; minium ("red lead'), or lead ortho-plumbate; realgar, or red sulphide of arsenic; lirtinswick green, or oxychloride of copper; Sclierle's green, or copiier ar.senite; tiehwf infurt green, a mixture of copper acetate and .Silieele's green; cobalt green, or cobalt and zinc oxide; umber, or baown silicate of iron and manganese; native or artificial brown ochres, i.e. earths colored by iron oxide; Berlin blue, or ferrocyanide or iron; Thenard's blue, or alu- minate of cobalt; ultramarine blue, a compound of aluminum, sodium, silicon, oxygen, and sul- phur; etc. The principal mineral colors are de- scribed in special articles or in connection with the metals or acids combined in them. See also P.MNTS; Painters' Colohs. MINERAL DEPOSITS. See Ore Deposits ; and the articles on the ilitl'erent ores and min- erals. MINERALOGY (by haplology for *mincral- oltiijy, from mineral, l)F. mineral. Fr. mineral, from ML. minerall, ore, from minera. mineria, minaria, mine, from minerurius. pertaining to mines, from minare, to mine, lead here and there, l.at. to drive, from minari. to threaten, from miner, threats, from minerc, to jut out + -Xo7la, -logia, account, fnmi eyeiv, legein, to say). The science of those natural substances known as minerals which, together or separately, form the material of the earth's crust, and also, as far as our knowledge extends, that of other celes- tial bodies. A mineral is a substance of definite chemical composition which has been directly prodiced by the prix'csses of inorganic nature. It must be honuigeneous even when submitted to minute microscopic examination, and must pos- sess a definite composition capable of being ex- pressed by a chemical formtila. Laboratory and furnace products, or such substances as shells ami bones of animals, cannot be included in the range of mineralogy. It is the function of the mineralo- gist to investigate the form, properties, and com- position of minerals: their genesis; their rela- tions to one ancither, and to the accompanying rocks; the places where they arc found; and the geological conditions under which they are formed, .V knowledge of mineralogy is of importance to the geologist in his study of the rock formations, to the mining engineer in his search for metal- producing minerals, and to the metallurgist in the extraction of metals from minerals. Many of (he useful arts are directly dependent for their raw materials upon minerals, while some mineral species oi'cur in such brilliancy and beauty of color as to be highly jiri/ed as gems. TiiK TtitANTiTES OF MiXKRAi.ofiY. The general subject of mineralogc may be divided into fotir sections: (1) Crystalhigraphy. which includes the description of crystals, their character, clas- sification, the mathematical relations of their
