LIME. 



The fiinilarity which fom? writers find between the pca- 

 ftonc and the variety of compact lime-llone, called roe-ilone, 

 •is not found in reality. 



Lime may he obtained in a (late of abfohite purity, by 

 feveral proceflcs from the native fubllanccR containing this 

 earth. The analyfia of the carbonats of lime is by far 

 the mod fimple, cfpecially when no other earth or metallic 

 oxyd is prcfent. This is pretty much the cafe with feveral 

 of the marbles, particularly the white or llatuary marble. 

 If the lime in any of thefe fuhdances be combined with no 

 other acid but the carbonic, let. loo grains in fine powder 

 be diffolvcd in m'.:riatic acid. If there be any rtTiduum, it 

 may be confidered as filcx, or fomc fait of lime not decom- 

 pofable by the muriatic acid, and mull be fet apart. Add 

 to the muriatic folution as much pure ammonia as will 

 make it fmell of this alkali, and all the earths, excepting 



■lime, with metallic oxyds, if there be any, will be preci- 

 pitated, leaving the liir.e in folution. If no fubltance be 



■fufpeftcd which is foluhle in am ronia, the lime may be con- 

 fidered as feparated from the o'her fiibllanccs, and if futh 

 a fui'picion iliould exiil, the fubftance may be feparated by 

 adding only jud as much ammonia as will make the folation 

 neutral. The lime may be precipitated from the acid with 



■carbonat of potafli, or that fait cnnimonly called the fub- 

 carbonat, by which a carbonat of lime is obtained. This 

 white powder, being feparated, mull be expofcd to a llrong 

 heat in a platina crucible, to feparate the carbonic acid, 

 which leaves the lime in a ilate of purity. 'Ihe precipitates 



-by the ammonia may confid of mai;neria, iron, and ibme- 

 times manganefe. The magnefia and manganefe will be 

 diffolved by adding a folution of fuper-carbonat of potafh, 

 leaving the oxyd of iron behind, which mull be wafhed and 



•dried. The manganefe may be precipitated by the h) dro- 

 fulphuret of potafh in a flate of fulphuret of manganefe, 

 which being wafiied, dried, and expofcd to a (Irong heat in 

 a platina crucible to expel the fulphur, will leave the pure 

 oxyd of manganefe. The magnefia, which is yet held in 

 folution by the excefs of carbonic acid, may be, finally 

 precipitated by pure potafh. The precipitate, being fepa- 



•rated, may be cxpofed to a (Irong heat in a platina crixible, 

 which will give this earth in a (late of purity. The refnlt- 

 ing r.ibllances, on being weighed, will not amount to the 

 original weight of the hme-llone; for, independent of the 

 lofs by analylis, alloivanee mull be made for the lofs of car- 

 bonic acid and water. The to;al amount of the latter filh- 

 ftances may be knov.n, by cxpofing a given weight in pow- 

 der in a platina crucible. The lofs by weight will be car- 

 bonic acid and water. If the carbon;c acid alone be 

 required, let a given weight in powder be taken, and let a 

 quantity of dilute fulphuric acid, amply fufificient to faturate 

 all the fubllanccs, be accurately weighed ; then let the 

 acid and powder be rr.i.xed together, and (lirred till the effer- 

 vefcence ceafes : afterwards weigh the mafs ; the lofs of 



■weight will be carbonic acid. The fame may be afccrtained 

 by putting the powder iuto a gas bottle, and adding mu- 

 riatic acid by degrees from an acid hohler, and then col- 

 IcCling the gas in lime-water. The carbonat of lime fo col- 

 le£lcd being weighed, 4J of carbonic acid may be allowed 

 for every 100 of the carbonat. 



The example given is fuppofed to be the mod compli- 

 cated of the carbonats of lime. If filcx be a component 

 part, it will be feparated in the lird folution, and mud be 

 wadied and dried. Manganefe is feldom found in lime- 

 ftone. It is faid to conttitute the property which fome 

 lime has of fetting under water. 



The native fulphat of lime or gypfum may be analyftd 

 by the following procefs. Let a iumdred grains of the 



cryftallized fait, in (lue powder, be cxpofed to a red heat 

 for fome time : the lofs by this treatment is the water of 

 cryihdhzation. Let the powder, after weighing, be boiled 

 for fome time in a folution of pure carbonat of potafh, 

 by which is obtained a carbonat of lime, and a fa phat of 

 potafti, the latter being foluble, and the forjner inloluble. 

 To the fulphat of potafh, when feparated, add muriat of ba- 

 rytes, and the fulphuric acid will be precipitated combined 

 with the barytes. For every 100 of this fait, allow 53.3 

 of acid, by which the proportion of fulphuric acid will be 

 known. 



The infoluble matter firll produced will confid of car- 

 bonat of lime, and perhaps iron. By adding to this the 

 fupercarbonat of potalh, the whole of the lime will be 

 didblved, but the oxyd of iron will be left behind. 



The lime which is diffolved by the fuper-carbonat of 

 potafli may be precipitated in the date of carbonat, and 

 made pure by a drong heat in a platina crucible, to drive 

 olf the carbonic acid. 



Phofphate of lime is analyfed by diffolving the native 

 crylfals in nitric acid, and adding to the fol'.;tion acetat, or 

 nitrat of lead, till no more is precipitated : the fubllaiice is 

 the phofphat of lead, whicli being feparated and weighed, 

 will determine the quantity of pholphoric acid, by allowing 

 iS.4 of acid for every 100 of the phofphat of lead. The 

 lime which is dilTolved in the nitric acid may be precipi- 

 tated by carbonat of potadi. 



The fiuat of lime may be analyfed by fird boiling it in a 

 date of fine powder with carbonat of potalh, or (oda, by 

 which a fluat of potalh or foda is obtained, from which the 

 fluoric acid may be again precipitated by acetat or nitrat 

 of lead, from which the proportion of fluoric acid may be 

 obtained. 



The llrd refiduum, which is carbonat of lime, and gene- 

 rrlly oxyd of iron, mud be treated as in the analylis of ful- 

 phat of lime, to feparate the oxyd of iron from\he lime. 



The native borat of lime contains more magnefia than 

 lime ; for its analyfis, fee the Borat of Alngnejia. 



Chemical Properties of Lime. — To obtain lime in a pure 

 date, the moll perfect cryllals of the carbonat (hould be 

 put into a covered vefTel, and expofed to a drong heat, con- 

 llderably above redncfs, for feveral hours. The crydals 

 will retain their fhape, but will have lod their tranfparcncy, 

 and become beautifully white. By this procefs the car- 

 bonic acid and water of crydallization are expelled, leaving 

 the lime in a date of purity. 



The lime thus cbt.iined has acaudic alkahnetade, and hke 

 bodies of thofe qualities, to a certain degree, dedroyi the tex- 

 ture of the fkiii, and in other refpefts afts upon animal fub- 

 flances in general : it alfo changes vegetable blues to green. 

 Its fpccific gravity is various ; according to Kirwan it is 2.3. 

 In this date it is called quick-lime. Its hardnefs, imme- 

 diately after it is produced from the carbonat, is not much 

 diminifhed ; but if expofed to tlie air for a certain time, it 

 falls into an impalpable powder, which appears of a more 

 fplendid white than in the folid date. 



In afiuming this form by cxpofure, it is found to be 

 heavier by one-third of its original weight. For this fadl 

 we are indebted to Mr. Dalton, who terms lime in this 

 date an hydrat of lime. 



If it be expofed to the air a longer time, it combines with 

 carbonic acid, and would ultimately acquire the original 

 weight of the sarbonat. 



When water is poured upon newly burned lime, it 

 quickly fwells with a hifTing noii'e, abfurbing the water with 

 great avidity, while much heat and even light are evolved. 



Thefe 



