1836.] 



FARMERS' REGISTER, 



81 



instance, and the cultivated crops subsequently, 

 are found to be greatly benefited. But in what- 

 ever manner iliis powerl'ui stimulant is applied, 

 the soil should never be altervvards exhausted by 

 a succession of grain-bearing crops — a justly-ex- 

 ploiled practice, which has reduced some naturally 

 itiriile tracts to a state of almost irremediable ster- 

 ility.' 



To point out the precise c{J|_>cts of lime, and the 

 proper quantity to be applied, to the extent to 

 which it has been already ascertained, would 

 greaily exceed the limits ol" this publication; and 

 were it possible to define its powers upon every 

 gradation of soil, a series ot" ex|)eriments would be 

 required which would occupy the labor of a long 

 life. Its qualities, too, difler materially in various 

 places, Irom the greater or less quantities of ex- 

 traneous substances with which it is combined. It 

 is very rarely that any farmer can obtain a choice 

 of lime, and when only one species can be pro- 

 cured he must be content with it; but he may, 

 nevertheless, be benefited by the following obser- 

 vations. 



Qualities and quantify of lime. 



Pure limestone, or chalk, when fully calcined, is 

 reduced to a fine impalpable powder, that feels 

 soft within the fingers, without tlie smallest tenden- 

 cy to grittiness: but such lime as contains sand is 

 neither so soft nor fine, but feels more or less gritty 

 in proportion as the sand is coarser or finer, and 

 more or less in proportion. Commonly, the 

 whitest lime is the best: when perfectly calcined, 

 it is generally of a bright white, without any 

 shade of color, and if clouded, it is thoiight to 

 proceed from a mixture of other matter; but the 

 color is not an infallible criterion, for dark colored 

 lime has, in some few instances, been found 

 stronger than that which was perfectly white. 

 The purer and the stronger the lime is, the lighter 

 also it will be found when weighed. Hence it fol- 

 lows, that the best lime for the farmer's use is that 

 which is the softest to the touch, the whitest, and 

 the lightest. 



The other simple tests fjr ascertaining its qual- 

 ity, which will be found sufficient to decide upon 

 the comparative value of any two kinds of lime, 

 and may be relied upon as sufficiently accurate for 

 the common purposes of the farmer, are as fol- 

 lows: — if the limestone loses much of its weight 

 in calcination, and the lime-shells are extremely 

 light — if the shells require a very large proportion 

 of water to slake them fully — if it is" long before 

 they begin to fall — if the limestone is not apt to 

 run (or to become vitrified) in ihe operation of 

 burning — if it falls entirely when it gets a sufficient 

 quantity of water, after it has been properly cal- 

 cined — if it swells very much in slaking, and if 

 the lime is light, fine to the touch, and of a pure 

 white — he may be satisfied that it is extremely 

 good, and he may use it in preference to other lime 

 that is inferior to it in any of these respects. The 

 presence of lime may also be discovered by its ef- 

 fervescence, or ebullition, on being exposed to 

 common vinegar.* 



*More detailed information on the mode of pursuing 

 experiments on lime may be obtained from Anderson's 

 Essays, Essay vi. part ii. sect. 11, 12 and l.S, p. 88, 



Vol. IV. -11 



I When quick-lime, too, is completely sifted 

 through a fine hair-cloth, that is the strongest 

 which leaves upon the cloth specifically the small- 

 est of earthy or sandy particles; and that, also, of 

 which the smallest quantity, when spread upon 

 the same space of ground in soils of equal quality, 

 will the soonest burn up the surliice of the grass. 

 Ws may also add, upon the authority of Sir Hum- 

 phry Davy, that lime, when slaked with sea-wa- 

 ter, has been used in some cases with considera- 

 bly more benefit than when wetted in the common 

 manner. 



The fierefit which might be derived from the 

 union of a slight portion of chemical skill with ag- 

 ricultural knowledge is perhaps incalculable. The 

 present state of education among the generality of 

 liirmersis not such, however, as to enable them 

 to reap much advantage from scientific experi- 

 ments, and even chemists rarely have opportuni- 

 ties of applying their art to practical purposes of 

 this kind. It may, however, prove uscfijl to some 

 to offer a few brief directions for the analysis of 

 lime, which we extract from the recent work of 

 Dr. Henry: — • 



'To determine the purity of lime, let a given 

 weight be dissolved in diluted muriatic acid. Let 

 a little excess of acid be added, that no portion 

 may remain undissolved owing the deficiency of 

 the solvent. Ddute with distilled water; let the 

 insoluble part, if any, subside, and the clear liquor 

 t)e decanted. Wash the sediment with fijrther 

 portions of water, and pour it upon a filter, previ- 

 ously weighed. Dry the filter, and ascertain its 

 increase of weight, which will indicate how much 

 insoluble matter the quantitj^ of lime submitted to 

 experiment contained. It is easy to judge, by the 

 external qualities of the insoluble portion, whether 

 argillaceous earth abounds in its composition*,' 



The presence of magnesia in limestone has been 

 considered pernicious to vefretation when burnt in- 

 to lime. It had been long known to farmers in the 

 neighborhood of Doncaster, and other parts of 

 Yorkshire, Derby and Nottinfrham, that lime 

 made from a peculiar species of limestone injured 

 their crops, and that made from the Breedon lime- 

 stone, in Leicestershire, which there goes under 

 the denomination of 'hot lime,' is so powerful, that 

 it is there seldom used in larger quantities than 

 from 25 to 30 bushels an acre, unless the land be 

 very rich. A series ofexoeriments were made up- 

 on the former by JVlr. Tennant, who discovered 

 that it contained magnesia, and on mixing some 

 calcined pure magnesia with earth, in which he 

 sowed different kinds of seeds, he found that 

 they either died or vegetated very imperfectlj-; he 

 therefore came to the conclusion that its eflijcts 

 v/cre prejudicial. This is thought to have been 

 occasioned by its retainino; its caustic quality lon- 

 ger than pure lime; and that, if used to excess, it 

 has a poisonous effect on vegetables, though, 'on 

 poor soils,' it has been said, neither to receive wa- 

 ter so rapidly, nor to part with it so freely, as lime; 



from the substance of which the foregoino; is chiefly 

 extracted. Our farming readers will also find an am- 

 ple discussion regarding the analysis of lime, in the 

 following volumes of the Farmer's Magazine, v. pp. 

 27, 26.5,'451; vi. pp. 11, 192, 312, 316; vii. pp. 26, 33, 

 and in Sir Humphry Davy's 7th lecture. 



* Elements of Experimental Chemistry, 10th edit., 

 vol. ii. chap. xv. sect, iii- 



