Page:Encyclopædia Britannica, Ninth Edition, v. 14.djvu/670

 L I M L I M bonatc CaC0 3 may be prepared by passing carbonic acid into lime-water. But a more convenient method is to decompose a solution of pure chloride of calcium with excess of carbonate of ammonia, preferably at 70-80 C., when the carbonate assumes the form of a crystalline precipitate which settles readily and is easily washed with hot water. The sulphate (artificial gypsum) appears as a voluminous white precipitate, consisting of minute colourless needles, when sulphuric acid is added to a riot too dilute solution of chloride of calcium or other lime salt. The precipitate CaS0 4 .2H 2 is appreciably solubb in water, 1000 parts of which at 0, 35, and 100 C. dissolve 2 05, 2 54, and a little over 2 parts respectively of gypsum. The hydrated sulphate at temperatures exceeding 110 J C. loses its water. The anhydrous sulphate, if formed below about 200 C., readily recora bines with water into compact gypsum (plaster of Paris). By exposure to high temperatures (500 C. and iipwards) sulphate of lime loses its power of recombining with water ; at very high temperatures it fuses. A naturally anhydrous sulphate of lime (anhydrite) occurs in association with rock salt, and otherwise, as a not very common mineral. The well-known favourable action of gypsum as a manure, more especially for clover (see AGRICULTURE), has lately been explained by De herain on the strength of analyses and vegetation experiments of his own, by assuming that it converts the carbonate of potash of the soil into sulphate, which, being less obstinately retained by the soil, more readily finds its way into the roots of the plants. Chloride of Calcium (muriate of lime), CaCl 2, is prepared by dis solving marble or limestone in aqueous muriatic acid. The iron and manganese generally present as impurities can be eliminated, after peroxidation by chlorine water, by digestion with hydrate of lime, which also, if allowed sufficient time, removes the magnesia. The liltrate is acidified with hydrochloric acid and concentrated by evaporation, so far that, on cooling, it deposits part of the dissolved salt as crystals. These have the composition CaCl. 2 . 6H 2 0. They are very easily soluble in water and alcohol, and highly hygroscopic. Hence the salt is used occasionally to keep textile fibres moist and in a fit state for being woven. The crystals when kept in a basin at about 200 lose about two-thirds of their water, and leave that porous kind of chloride of calcium which analytical chemists prefer for the drying of gases. This substance, when heated to redness which must be done in platinum to prevent contamination loses the rest of the water and (at 723 C., Carnelley) fuses into the anhydrous salt CaCl 2, which on cooling hardens into a stone-like mass. In this final process of dehydration, however, part of the chlorine goes ofT as hydrochloric acid, so that the product obtained is contaminated with some oxychloride. This can be prevented by igniting the salt with sal-ammoniac or more surely by effecting the dehydration in a current of anhydrous hydro chloric acid gas. Anhydrous chloride of calcium is much used in laboratories as a powerful dehydrating agent. It combines with ammonia gas into a solid compound. It dissolves in methyl alcohol and in ethyl alcohol, forming crystallizable &quot; alcoholates&quot; (Graham), compounds of CaCl 2 with &quot; crystal alcohol.&quot; Nitrate of Calcium, Ca(N0 3 ) 2, crystallizing with 4H 2 0, is a very hygroscopic salt, soluble in even absolute alcohol. It is mentioned here as a material for the convenient preparation of pure lime by simple ignition of the salt in a platinum crucible. Regarding bleaching powder, a double salt of hypochlorite and chloride of calcium Cl-Ca- (CIO), see CHLORIXK, vol. v. p. 678. Fluoride of Calcium, CaF a, obtainable by precipitation of chloride of calcium with an alkaline fluoride, occurs in nature as Furor.srAR (q.v. ). Fluoride of calcium is widely disseminated throughout the mineral kingdom as an admixture with other minerals. All native forms of phosphate of lime contain it ; some in considerable quantity. Traces of it are found in bones and in the ashes of most plants. Metallic Calcium cannot be prepared by the reduction of the oxide with charcoal. It may be produced, however, by the electro lysis of the fused chloride or more conveniently by heating the iodide CaI 2 (seven parts) with sodium (one part) in an iron crucible. The metal has a yellow colour; it is somewhat harder than lead, and very malleable and ductile (Lies-Bodart and Jobin). The specific gravity is 1 578 (Bunsen and Matthicson). It does not tarnish in dry air, but readily decomposes water, with evolution of hydrogen anl formation of hydrate of lime. It is practically non-volatile. When heated in air or oxygen it burns with a most brilliant light into oxide, CaO. Tests. Solutions of ordinary calcium salts are not affected visibly by sulphuretted hydrogen, sulphide of ammonium, or pure ammonia. Carbonate of ammonia, even in the presence of sal-ammoniac, pre cipitates the carbonate. So far calcium behaves like barium and strontium. From the former it is distinguished by its not being precipitated by either hydrofiuosilicic acid or bichromate of potash, and from both by its spectrum and the relatively large solubility of its sulphate in water. The latter is obtained from any calcium solution by addition of sulphuric acid and alcohol. The sulphate is washed with alcohol on a filter. When then boiled with water it yields a solution which, dilute as it is, gives a very distinct pre cipitate with oxalate of ammonia (barium and strontium sulphates in these circumstances give negative results). Oxalate of ammonia is the most delicate precipitant for calcium ; the precipitate is in soluble in water, in ammonia and ammonia salts, and in acetic acid. From solutions (in acids) of phosphate or oxalate of calcium ammonia and likewise sulphide of ammonium precipitate the metal as phosphate or oxalate. To detect it in such a precipitate, dis solve in hydrochloric acid and add sulphuric acid and alcohol. The calcium is precipitated as sulphate, which can be identified as just explained. For the phosphates of lime, see PHOSPHATES. (W. D. ) LIME, or LINDEN. The lime trees, species of Tilia, are familiar timber trees with mellifluous Howers, rarely if ever maturing their fruit in England, which are borne on a common peduncle proceeding from the middle of a long bract. T. europeea, L., is indigenous to Europe, except ing the extreme north, and extends eastwards across Russian Asia to the Altai. The lime is much planted in Britain, and is probably wild in south and west England, and perhaps iu Ireland. The truly indigenous form in north Europe is always a small-leaved one. The large leaved variety (T. f/randifolia, Ehrh.) is of South-European origin (Bentham, Handbook of the British Flora, i. 157); T. parvifolia, L., is perhaps the English, wild form of the Continental T. europxa, L. ; while T. intermedia, D. C., probably a sub-species of T. euro])$ea, L., is the so-called common lime (Hooker, Student s Flora of the British Isles, p. 76). For a full description of the European and American forms, see Loudon, Arboretum, i. p. 364, and De Can-dolle, Prod., i. 513. The lime sometimes acquires a great size : one is recorded in Norfolk as being 16 yards in circumference, and Ray mentions one of the same girth. The famous linden tree which gave the town of Xeustadt in Wiirtemburg the name of &quot; Neustadt an der grossen Linden&quot; was 9 feet in diameter. The economic value of the tree chiefly lies in the inner bark or liber, called bast, and the wood. The former was used for paoer and mats and for tying garlands by the ancients (Oil., i. 38 ; 1 liny, xvi. 14, 25; xxiv. 8, 33). T. grandifolia and T. parvifolia have been found in the debris of lake dwellings in Switzerland. Bast mats are now made chiefly in Russia, the bark being cut in long strips, when the liber is easily separable from the corky superficial layer. It is then plaited into mats about 2 yards square ; 14,000,000 come to Britain annually, chiefly from Archangel. The wood is used by carvers, being solt and light, and by architects in framing the models of build ings. Turners use it for light bowls, &c. The flowers, alone, are used for an infusion in Austria and elsewhere, with much success in vertigo and spasms, producing perspiration, and alleviating coughs ; but the bracts and fruit are astringent. The common lime was well known to the ancients. Theophras- tus says the leaves are sweet and used for fodder for most kinds of cattle. Pliny alludes to the use of the liber and wood, and describes the tree as growing in the mountain valleys of Italy (xvi. 30). See also Virg., Gco., i. 173, &c. ; Ov., Met., viii. 621, x. 92. The &amp;lt;f&amp;gt; tvpa (Hdt. , 4. 67) was the lime of the Greeks, perhaps T. argentca (see Pickering s Chron. Hist, of Plants, pp. 214, 227, 418). Allusion to the lightness of the wood is made in Aristoph., Birds, 1378. Fcr the sweet lime (Citrus Limctta) and lime juice, see LEMON. LIMERICK, a maritime county of Ireland, in the province of Munster, is bounded on the N. by the estuary of the Shannon and the counties of Clare and Tipperary, on the E. by Tipperary, on the S. by Cork, and on the W. by Kerry. Its greatest length from north to south is 35 miles, and its greatest breadth east and west 54 miles. The total area comprises 662,973 acres, or 1036 square miles. The greater part of the county is comparatively level, and rests on limestone, but in the south-east the picturesque Galtees, which extend into Tipperary, and are composed of Silurian strata overlaid by Old Red Sandstone, attain in Galtymore a height of 3015 feet, and on the west stretching