ON MANURES. 95 



purer and the stronger the lime is, the lighter also it will be 

 found when weighed. Hence it follows, 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 for ascertaining its quality, which 

 will be found sufficient to decide upon the comparative value 

 of any two kinds of lime, and may be relied upon as suffi- 

 ciently accurate for the common purposes of tlie farmer, are 

 as follows: — If the limestone loses much of its weight in cal- 

 cination, 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 tiie limestone 

 is not apt to run (or to become vitrified) in the operation of 

 burning; — if it falls entirely when it gets a sufficient quantity 

 of water, after it has been properly calcined; — if it swells very 

 nmch 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 effervescence, or ebullition, on 

 being exposed to common vinegar. 



When quicklime, too, is completely sifted through a fine 

 hair-cloth, that is the strongest which leaves upon the cloth 

 specifically the smallest 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 surface of the grass. We may also add, upon the 

 authority of Sir Humphry Davy, that lime, when slaked with 

 sea-water, has been used in some cases with considerably more 

 benefit than when wetted in the common manner. 



The benefit which might be derived from the union of a 

 slight portion of chemical skill with agricultural knowledge 

 is perhaps incalculable. The present state of education among 

 the generality of farmers is not such, however, as to enable 

 them to reap much advantage from scientific experiments, and 

 even chemists rarely have opportunities of applying their art 

 to practical purposes of this kind. It may, however, prove 

 useful to some to ofler a ^ew 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 wei?lit be dissolved in di- 

 luted muriatic acid. Let a little excess of acid be added, that no portion may 

 reniHin undissolved, owing to the deficiency of the solvent. Dilate with dis- 

 tilled water ; let the insoluble part, if any, suttside, and the clear liquor be 

 decanted. Wash the sediment with further portions of water, and pour it 

 I 2 



