__: . On as€e?''tcnj2ing the ^jjality cf Lime. - \^ Feb, 



f .<v* 



cafes where the fuel is only to1)e got near home. In general, 

 it is moft prcfitviblc to carry off limeftone as foon as burnt, in 

 order to avoid weight of carri<i;^e, becaufe, whenever it again 

 grows cold, it begins to imbibe its carbonic acid from the atmof- 

 phere. 



If lime is not pure, it is obvious that it will lofe a great dQ^\ 

 lefs weight in burning than pure lime. Hence arifes another 

 criterion for trying tl.e goodn.ifo cf lime-fhells. The lig'iter they 

 are iov thtir buik^ or the more v.cight they lofe in burning t])e 

 better. VVei^h a piece of llmeiione, burn it proL^erly, then 

 -wcigf? it again. If it has loll a^ much as two-fifths of its weight 

 \>y burning, it i:> good iime. 



Unburnt iimeflone feldom contains mo'^c than eighty ;:€r cent, 

 of pure qtvaW. or caibcnate of lime. Pitleilie quarry ir, Fife be- 

 longing to !vlr Low of Anr.field has one Stratum containing 994 

 per cent 01 carbonate cf lime, which is iruj pureft iimcilone I 

 have ever heard of. Perhaps, however, fornc fine marbles may 

 be even more pure. 



The colour of lime is no criterion of its ^oodncfs; for inftance, 

 Abe;\;o-ir lime, which is blue, was founJ, on a comparative trial, 

 to be. richer than a quantity of Sunderland lime, which was of a 

 bright white colour, indicating purity in the general opinion. 



Anotlier method of trying the comparative goodnefs of lime, 

 is by afccrtaining 'vhat quantity of proper mortar fit for building 

 (and which ihould fall readily off the mafon's trowel) can be made 

 from a given quantity of lime-fhells. As this may be done eafily 

 on a large fcale, it i:, in my humble appreheniion, the bell me- 

 thod of trial, bccaufe a large quantity of lime mcAi generally con- 

 tains a due mixture and proportion of all iV.t 'dil'ererit flrata of 

 the rock which are frequently exceedingly different in quality. 



Some limes require no fand at all to make mortar for building ; 

 and thefe are efteemcd by intelligent mafons the bed for archi- 

 tedlure, as making the Urongeil cement. But fuch limellone, 

 containing perhaps more than tliree fourths of its bulk of fand, 

 can feldom be applied witli economy to the purpofes of agricul- 

 ture. 



I was once judge of a comparative trial by mafons of two car- 

 goes of lime-Qiells, each of which was accounted excellent. The 

 one was from the neighbourhood of Aberdour of a quarry be- 

 longing to the Earl ot Morton, the other from a quarry in the vi- 

 ciniry of Edinburgh. The lime-ftiells of Aberdour, when Hack- 

 ed, produced three times their quantity of pov.dered lime ; and 

 that jjowdered lime lequired three times its quantity of clean 

 land to Drake good mortar for building. In other words, each 

 boll of Aberdour lime-lhells, by being watered, became three 

 bolli of quick lime powder, and each boll of the powder became 



good 



