L I M 



[259 ] 



LI M 



3. In botany, the outer spreading 

 portion of a monopetalous corolla. 



LI'MBILITE. (from Limbourg, in 

 Swabia.) A compact mineral of a 

 honey-yellow colour, supposed to 

 be a decomposed olivine. On ex- 

 posure to the action of the blow- 

 pipe, it fuses into a compact, 

 shining, black enamel. 



LIME. The protoxide of calcium, one 

 hundred parts consisting of 72 of 

 calcium, its metallic basis, and 

 28 of oxygen. Lime does not exist 

 in a pure state in nature, it has so 

 strong an affinity for carbonic acid 

 as to absorb it from the atmosphere, 

 when it becomes converted into 

 carbonate of lime, constituting the 

 different kinds of marble, chalk, 

 and limestone, and forming exten- 

 sive strata, and the largest moun- 

 tain ranges. Lime is a white or 

 light grey earth, fusible only by 

 the heat of a galvanic battery, or 

 of a gas blow-pipe ; it is exceeding- 

 ly caustic, and if water be sprinkled 

 upon it, great heat is produced, the 

 water unites with the lime, forming 

 a hydrate of lime. Lime is 

 partially soluble in water, and 

 there is a singular circumstance 

 connected with this, namely, that 

 cold water dissolves a larger pro- 

 portion than hot water. Specific 

 gravity 2 '3. 



LI'MESTONE. A genus of minerals 

 comprising many species. How- 

 ever various in external appear- 

 ance limestone may be, it is, if 

 pure, essentially composed of 57 

 parts of lime and 43 carbonic acid ; 

 but in some rocks the limestone is 

 intermixed with magnesia, alumine, 

 silex, or iron. The specific gravity 

 ef limestone varies from 2-50 to 

 2.80. All limestones may be scra- 

 ped with a knife. They are infu- 

 sible ; but when impure, by an in- 

 termixture with a portion of other 

 earths, they vitrify in burning. 

 All limestones effervesce when a 

 drop of strong acid is applied on 



the surface ; and they dissolve 

 entirely in nitric or muriatic acid. 

 The specific gravity, hardness, and 

 effervescence with acids, taken 

 collectively, distinguish limestone 

 from all other minerals. 



The whole of the limestone de- 

 posits have been arranged into the 

 following suite. In the inferior or 

 primary order, crystalline marbles ; 

 in the transition and carboniferous 

 orders, compact and sub-crystalline 

 limestones; in the secondary, less 

 compact limestone, calcareous free- 

 stone, and chalk; in the tertiary 

 or supracretaceous order, loose 

 earthy limestones. 



Primary limestone has always a 

 granular structure ; but the size of 

 the grains is variable, and seems, 

 in some degree, to correspond with 

 the relative age of the mineral. 

 Thus the limestone, which occurs 

 in beds in gneiss, and which is 

 supposed to belong to the older 

 formations, has usually a coarse 

 texture, and large granular concre- 

 tions. But when its beds exist in 

 mica slate, or argillite, its texture 

 becomes more finely grained, and 

 its colour less uniform. Transition 

 limestone has a texture more or less 

 compact; its colours are much 

 variegated; and it often contains 

 petrifactions. Secondary limestone 

 has a compact texture, a dull frac- 

 ture, and usually contains shells, 

 and sometimes other organic re- 

 mains. It is always stratified; 

 bat the strata are sometimes in- 

 clined, sometimes horizontal. 



Sir H. Be La Beche states the 

 quantity of lime in granite com- 

 posed of two-fifths quartz, two- 

 fifths felspar, and one-fifth mica, to 

 be 0-37 ; and in greenstone, com- 

 posed of equal parts of felspar and 

 hornblende, to be 7'29. 

 LIMN^J'A. j (from Tu/tj/as, a marsh, or 

 LIMNE'US. ) pool, Gr.) A genus of 

 fresh water univalves, placed by 

 Cuvier in the order Pulmonea, class 



