266 1'hoiighfs on the Analyfaiion of Lime ^ ^c. -'^ug. 



chemlils by the name Carbonate of lime, implying, what A. S. 

 feems to know, that it is the refult of the combination of lime (not 

 yet afcertained to be an alkali, thouc;h it has properties in com- 

 mon with alkalis, but confidered at prefent as an earth) and 

 carbonic acid, which probably, in its union with lime, lofes 

 the form of iias or air, although, when feparated from the earthy 

 it takes that form. A. S. is in a proditiious error, when he di- 

 re6ls us to buy muriatic acid from any Laboratory. The com- 

 mon acid of the lliops will caufe abundance of fediment to ap- 

 pear, even when the limeftone is perfectly pure. I liave had 

 occafion to ufe about as much muriatic acid as mod amateurs oF 

 the art of chemical analyfis, and I can aflure A. iS. I never yet 

 found any acid which did not occafion me confulerable pains to 

 purify. It always contained more or Icfs fulphuric acid, which 

 gets accefs to it in the common proccfs for obtaining it; and 

 this acid, with lime, forms an infJuble compound, called ful- 

 phate of Ijme, or gypfum. In this way, A. 8. will perceive that 

 tlie bcR of ten limeitones he may try, may appear, by his me- 

 thod of examination, to be the word. Unlefs, therefore, per- 

 fectly pure acid be ufed, the tcfl of A. S. is a deception. But 

 for the further information of A. S., and fuch of your readers 

 as may have adopted his recipe, let us fuppofe that the acid is 

 perfe6\ly /«r^ ; jtill the teft of the qua?it'ity of fediment is not fuf- 

 ficieut. Limeftones, befides lime, may, and almolt always do, 

 contain a variety of other earths, and fometimes metals, moil 

 frequently iron. Now, the only one of thefe earths that will be 

 left undilTblved is the filicious \ and if any inflammable matter 

 is contained in the limeftone, it will alfo be left. As to the re- 

 paration of the remaining earths from the folution, and from 

 each other, fo as to afcertain their proportion to the lime and to 

 each other, this requires manual flvill, exclufive of confiderable' 

 knowledge in chemillry, and which can be acquired only by the 

 greateil: care and patience. Now, of two limeitones, the one 

 which leaves leail: fediment may be the worfl:, and the other the 

 beft. If A. S. iludies the fubjecV, he will difcover that no fu- 

 perficial trials, fuch as he recommends, are of any ufe in afcer 

 raining the purity of limeftone. 



Without a regular analyfis by a fkilful chemlft, the real value 

 of limeftone cannot be afcertained. The only method with 

 which I am acquainted, and by whic!i we may have a tolerable 

 way of judging of the quality of limeftone, ivithout a regular ana- 

 l-'.i'sy is the following. H.iving provided pure acid, a fm.ill bot- 

 t.c, with a covk or glafs Itopper, and an occur, ite -a^w^ fenfihle ba- 

 Ijiice, and properly (i(ljifled^t\^\\\Si proceed as lollows. Weigh 

 tliC boitic, after having put in a quantity of acid, with its cork; 



having 



