LIMESTONE. 275 LIIOE-TBEE. cent, of lime carbonate, but in many others the percentage is much lower, due to the presence of mineral impurities such as silica, alumina, and lorric oxide. An appreciable quantity of car- bimaceous matter may also be present. This variation in composition is shown by the follow- ing analyses: I CaCOj... MgCO,.... SiOj .il.Oj I'e.Oj HjO Alkaliew.. 99.30 0.*9 0.63 0.55 52.75 1.S2 .55 1.82 43.91 2U.U 15.37 1.20 35.85 18. eo 38.11 ) 5.77 i 1.79 .41 1. White limestone. Adams, Mass. 2. Dolomitie llme- etoue, Ctiicugo, 111. 3. Hydraulic limestone, liuuduut, N. 1". 4. Calcareous saudstoue, Jordan, Miuu. Origin". Limestone may be formed in several ways: (1) By the accumulation of ori;anic re- mains or the growth of colonies with calcareous skeletons; the former manner of origin is illus- trated when shell-fragments and foraminiferal cases collect on the ocean bottom, and the latter is shown in the giowth of coral reefs. (2) By chemical precipitation. ilany spring waters hold lime in solution in the form of bicarbonate, but this compound on coming in contact with the air is broken up and lime carbonate precipi- tated. The same change is also caused by cer- tain minute algse and calcareous plants found growing in ponds. The lime carbonate deposited by springs often forms beautiful incrustations on mosses and other objects. The efl'cct of plant action is seen in the accumulation of marl in the bottom of many ponds. (3) By mechan- ical means. Calcareous rocks are broken down by wave-action, and the fragments strewn over the ocean bottom in time may form extensive strata. Propebties of Limestone. Pure limestone is white, but the presence of even small amounts of carbonaceous matter may color it black, gray, or blue, and iron will tinge it brown, yellow, or red. The texture varies from coarse to fine, and the rock may be either crystalline (marble) or eailhy (chalk); the layers range from massive to shaly. Limestone efl'ervesces readily with cold muriatic acid unless it is magnesian, when only warm acid attacks it. Most limestones are eas- ily soluble in water containing a slight quantity of carbonic or other acids, and hence their sur- face is sometimes quite uneven. The easy solu- Irility of the rock has led to the formation of caves and sinkholes. Since both sand and clay
- ne often washed into the waters where lime-
stones are forming, the rock may be siliceous or
- iluminous in its character, and by an increase of
lliese impurities, grades into sandstones on the one hand, or into sh.iles on the other, the inter- mediate varieties being called calcareous sand- stones and calcareous shales. Limestones show a wide geological distribution, being fotmd in everv- system, but their greatest development is among the Paleozoic formations, where a series of calcareous beds may sometimes attain a thick- ness of several hundred feet. The older lime- stones, geologically, are conimonlv crystalline, due to regional metaniorphism. but the later ones may at times be so either from this same cause or from contact metamorphisni. The geo- graphic distribution of limestones is equally great. Varieties of Limestone. A number of names have been given to different varieties of lime- stone, of which the more im])Ortant are the fol- lowing: Crinoidal limestone, a variety contain- ing fragments of crinoid stems. Coquina (q.v.), a variety composed of loosely cemented shell fragments. C'lialk (q.v.), a white variety of limestone formed chiefly of foraminiferal shells. Dolomite (q.v.), a limestone containing both car- bonate of lime and magnesia. Ui/ilniulic time- stone, an aluminous variety having the property of hardening under water after it has been burned. Marl (q.v.), a soft, calcareous mud, formed in the bottom of many ponds. Marble (q.v.), strictly speaking, is a crystalline limestone, but the term has been expanded in commercial use to include any limestone that will take a polish. Oolite (q.v.), a limestone composed of small spherical grains, flnechnroiilal limestone, a coarsely granular variety. Trnrer- line and tufa, calcareous deposits formed around the mouths of springs. Uses. The chief use of limestone is for build- ing purposes, for which it is found especially vahmble on account of its wide distribution, dense structure, and massive character. Marble is used for decorative work. Limestone is also widely used as a road material and in the manu- facture of lime (q.v.). When mixed with play or shale in certain proportions and burned and ground it forms Portland cement. Many argil- hueous limestones when burned also show hy- draulic properties, and such arc put on the mar- ket under the name of Rosendale or natural rock cement. Other uses of limestone are as a llux in iron and lead smelting, and in glass manufac- ture. When burned to lime it is employed for making mortar and chloride of lime: and is used in gas, soap, and sugar manufacture, as a disin- fectant, for bleaching, in the manufacture of Bessemer steel, etc. The total value of the lime- stone produced in the United States in 1001 was $26,406,897. Of this amount .$8.204.0.54 repre- sented the value of stone sold for lime for blast- furnace fltix. BiBLiOGRArnT. Burnham, Uistorti and Vses of Limestones and Marbles (Boston, 1883); Hop- kins, "Marbles and Other Limestones." Arkansas Geological Surre;/ Report, vol. iv. (Little Rock. 1S93) ; Lane, "Michigan Limestones and Their Uses," Engineering and Mining Journal (New York, 1900) ; Ries, "The Limestone Quarries of Eastern Xew York. Western Vermont, Massachu- setts, and Connecticut." United Slates Geologieal Siirreif Report (Washington. 1896) ; Ries. "The Limestones of Xew York and Their Economic 'alue." Annual Report of the ?Cew York State Geologist ( Albany, 1 900 ) . See Building-Stones ; Marble; Cement; Lime; INLabi,. LIME-TEEE, Linden, or LrxN (AS. limien, from lind. lindr. Icel. lind. OHG. linta. Ger. Linde, linden: probably connected with Ok. e/.arr/, elati, silver fir). . name given to trees of the genus Tilia, natural order Tiliacea". natives of Europe, the north of Asia, and North .Americn, Tlie spe- cies, which number about a dozen, are verv simi- lar; graceful, umhraaeons trees, with deciduous heart-shaped, serrated leaves, .-ind cymes or pani- cles of rather small yellowish flowers, each c>-me or panicle accompanied with a large., oblong, yel- lowish, membranous bract with netted veins, the
