473 



LIMK. 



strong pressure, so as to prevent the escape of the 

 carbonic will, it mny U- melted at a temperature 

 ev. 11 not |MK|:I r Ihftii 82 of VPedgWOed'l scale. By 

 tlii- lu-uui, it acquires considerable hardness ami 

 clo-eiie-s of [.-Mure, approaching, in tluv-e qualities, 

 ;is \v-ll as in fracture nd specific gravity, to the 

 finer kind- of marble. The acids expel the carbonic 

 acid wiih rflcr\ e-cence ; ;ind this property of eil'cr- 

 .: -ironnly. on I lie contact of an acid, a (lords a 

 di-cniiiinaiing character of this salt. C'arbouute of 

 lime alxninds in nature. 



Kitrate of lime may be formed by dissolving lime, 

 or its carbonate, in dilute nitric acid. The solution, 

 on evaporation . affords deliquescent, prismatic crys- 

 tals, soluble in less than an equal weight of water, 

 at the temperature of 60, and in still less of boiling 

 water. On being heated, it becomes phosphorescent, 

 and retains this property when cold, forming Bald- 

 wins solar phosphorus. It forms naturally in the 

 plaster of old buildings. 



Sulphate of lime is formed by adding lime to 

 dilute sulphuric acid. It requires about 500 times 

 its weight of water, at 60, for its solution. At the 

 temperature of 212*, it is more soluble, and this 

 latter solution, on cooling, deposits minute crystals. 

 Exposed to heat, it appears to effervesce, or boil, 

 owing to the expulsion of its water ; and, at the same 

 time, becomes opaque, and falls into a white powder 

 which, on being diffused in water, speedily consolidates 

 from a species of irregular crystallization. Sulphate 

 of lime is one of the most abundant minerals in nature. 



Phosphate of lime may be formed by decomposing 

 the solution of an alkaline phosphate by muriate of 

 lime. It is a white, insoluble powder, which is imper- 

 fectly vitrified by a very intense heat. It exists in 

 the mineral kingdom, under different forms, and con- 

 stitutes eighty-six per cent, of the bones of animals. 



Muriate of lime is obtained by dissolving carbon- 

 ate of lime in muriatic acid. It is extremely soluble 

 in water, the water taking up so much of it as to 

 become of a thick consistence. 



Lime in Agriculture. Quicklime, in its pure state, 

 whether in powder, or dissolved in water, is injurious 

 to plants. Grass is killed by watering it with lime- 

 water. But lime, in its state of combination with 

 carbonic acid, is a useful ingredient in soils. When 

 lime, whether freshly burned or slacked, is mixed with 

 any moist, fibrous, vegetable matter, there is a strong 

 action between the lime and the vegetable matter, and 

 they form a kind of compost together, of which a 

 part is usually soluble in water. By this means, 

 matter which was, before, comparatively inert, 

 becomes nutritive ; and, as charcoal and oxygen 

 abound in all vegetable matters, the lime becomes 

 converted into a carbonate. Mild lime, powdered 

 limestone, mark, or chalks, have no action of this 

 kind upon vegetable matter; by their action they 

 prevent the too rapid decomposition of substances 

 already dissolved; but they have no tendency to form 

 soluble matter. From these circumstances, it is 

 obvious, that the operation of quicklime and marl or 

 chalk, depends upon principles altogether different. 

 Quicklime, in the act of becoming mild, prepares 

 soluble out of insoluble matter. It is upon this 

 circumstance that the operation of lime, in the pre- 

 paration of wheat crops, depends, and its efficacy in 

 fertiliiiiiff peats, and in bringing into a state of culti- 

 vation all soils abounding in hard roots, or dry fibres, 

 or inert vegetable matter. The solution of the ques- 

 tion, whether quicklime ought to be applied to a soil, 

 depends upon the quantity of inert vegetable matter 

 it contains. The solution of the question, whether 

 marl, mild lime, or powdered limestone, ought to be 

 applied, depends upon the quantity of calcareous 

 matter already in the soil. All soils are improved 



by mild lime, and, ultimately, by quicklime, which 

 ilo not cllt'r\esce with acids; and sands are more 

 benefited by it than clays. When a soil, deficient in 

 calcareous matter, contains much soluble, vegetable 

 manure, the iij'|>lication of quicklime should always 

 Ix 1 avoided, as it either tends to decompose the solu- 

 ble matters by uniting to their carbon and oxygen, 

 so as to become mild lime; or it combines with the 

 soluble matters, and forms compounds having less 

 attraction for water than the pure vegetable sub- 

 stance. The case is the same with respect to most 

 animal manures ; but the operation of the lime is 

 different, in different cases, and depends upon the 

 nature of the animal matter. Lime forms a kind of 

 insoluble soap with oily matters, and then gradually 

 decomposes them by separating from them oxygen 

 and carbon. It combines, likewise, with the animal 

 acids, and probably assists their decomposition by 

 abstracting carbonaceous matter from them, com- 

 bined with oxygen; and consequently, it must render 

 them less nutritive. It tends to diminish, likewise, 

 the nutritive powers of albumen, from the same 

 causes, and always destroys, to a certain extent, the 

 efficacy of animal manures, either by combining with 

 certain of their elements, or by giving to them new 

 arrangements. Lime should never be applied with 

 animal manures, unless they are too rich, or for the 

 purpose of preventing noxious effluvia. It is injuri- 

 ous when mixed with any common dung, tending to 

 render the extractive matter insoluble. In those 

 cases in which fermentation is useful to produce 

 nutriment from vegetable substances, lime is always 

 efficacious, as with tanners' bark. (For the use of 

 lime in building, see Mortar.) Lime is much used 

 by tanners, skinners, &c., in the preparation of their 

 leather; by soap-boilers, for dissolving the oil, and 

 facilitating its union with the alkaline salt; and by 

 sugar-bakers, for refining their sugar. It is also ol 

 some medicinal use, being applied externally in de- 

 siccative and epulotic medicines. 



Native Salts of Lime, or Calcareous Minerals. 

 Of these, the first deserving of mention is the carbo- 

 nate of lime, limestone, or rhomboidal limestone. This 

 species, in mineralogy, is one which, from its wide 

 distribution, and the immense masses in which it 

 frequently occurs, constitutes an important rock in 

 geology. Its mineralogical character may be ex- 

 pressed as follows: Fundamental or primary form, 

 an obtuse rhomboid of 105 5' and 74 55'; secondary 

 crystals (of which above 600 are, at present, known) 

 are some variety of the rhomboid, the six-sided prism, 

 or of a double six-sided pyramid, all of which afford 

 the primitive rhomboid, by cleavage, with the most 

 perfect facility. No species in mineralogy is so 

 interesting to the crystallographer as the present. 

 To it we owe our first correct ideas of the internal 

 structure of crystals, and the best theory of crystal- 

 lization which has ever been suggested. Lustre 

 vitreous; prevalent colour white, also different shades 

 of gray, red, green, and yellow, and dark brown, 

 and black colours, from foreign admixtures; streak 

 grayish-white ; transparent to translucent ; double 

 refraction very considerable and easily observed ; 

 brittle; hardness such as to admit of being easily 

 impressed by the knife; specific gravity, 2'72. Be- 

 sides occurring in distinct crystals, it exists in stalac- 

 titic, botryoidal, and fruticose shapes, with surfaces 

 uneven, drusy, rough or smooth ; and composition 

 columnar, more or less distinct, straight, diverging, 

 and of various sizes. Stalactitic and botryoidal varie- 

 ties are often, composed, a second time, of curved 

 lamellar particles, conformably to the surface of the 

 imitative shape, the faces of composition being uneven 

 and rough, or irregularly streaked in a longitudinal 

 direction. It also occurs massive; the composition 



