i'804. On afcertaimng the ^inl'tty of Ltmefone, 273 



The magnefKin limeftone, according to Mr Tcnnant, may ea'-ly 

 be tUllinguiilicd from that wlilch is purely calcar'.""oir^, by the 

 flownefs of its folution in ycids, which is fo confide;! able, that 

 even the foftell kind of the former is nnuch longer i'l dllli-^Iviig 

 than marble. It has alfo frequently a cryflallizcd ftru:Uire ; :ind 

 fometimes, thou<:;h not always, imall black dots may b' fecn dif- 

 perfed through it. 



To afcertain, by chemical means, the compontion of lime or 

 limeftone, the following is an caly and accurate pro(^cfs. 



Let 100 grains of lime or limellone, well dricd^ be difTolv- 

 cd, without heat, in a fmall proportion of diluted muriaiic acid 

 (fpirit o{ fait.) 



If the folution contain only calcareous earth, it will givj no 

 precipitate with folution of pure ammonia (fpirit of fnl annno^iac.) 

 The phial containing the folution, fhould be inftnntly clofed, left 

 the ammonia fhould abforb carbonic acid (fixed air.) 

 - But it will afford a precipitate, when fulphuric acid (oil of vi- 

 triol), or carbonate of potafh (fait of tartar) is added. 



If it contain calcareous earth and magnefia, it will give a pre- 

 cipitate both with pure ammonia ;ind fulphuric acid : this latter 

 refult Is haftened by evaporation, or a flight addition of fpirit of 

 wine. 



Or the lime and magnefia may be feparated, by adding mode- 

 rately ftrong fulphuric acid to the muriatic folution, as long as 

 any precipitate appears, then heating the folution ilightly, and 

 adding fpirit of wine. The fulphate •of lime, thus precipitated, 

 being -filtered ofr, and heated gradually to rednefs for half an hour, 

 will then be dcficcated ; and of this, 100 grains will contain 

 nearly 39 of lime, which would form 70 grains of deficcated 

 limeftone. The magnefia may now be precipated from the mu- 

 riatic folution by carbonate of foda (fait of foda) \ then dried 

 and weighed. The quantity of each ingredient will thus be found 

 in the fame ftate as it exifted in the limeftone. 



I am yours, &c. 

 Tork/ljire^ 1804. Tyro. 



TO THE CONDUCTOR OF THE FARMER's MAGAZINE. 



On Drawing. 

 Sir, 



I have obferved in your ufeful Magazine, great attention be- 

 ftowed for the purpofe of afcertaining the btft method of drain- 

 ing -wet lands; and the fubjcft is furely^very defetving of it, — as 



S 4 low 



