ON MANURES. 83 



immediate crops.* We have, indeed, the opinion of a very 

 experienced farmer, who is also well versed in chemistry, 

 * that, should much rain immediately succeed the ploughing, 

 and any considerable portion of sand be either in the lime or 

 in the soil, it is almost a moral certainty that such soil will be 

 in a worse state than it was before the lime was put on, 

 because, the moisture being retained by the lime and the soil, 

 and the tenacity of the sub-stratum not suffering the super- 

 abundance to pass quickly away, it causes the whole to run 

 together, and form a compact and impervious bottom, which 

 before, however, might have been pervious in a slow degree. 

 That this must be the case is evident from this consideration, 

 that quicklime, mixed with a certain portion of sand, and duly 

 moistened, contracts and forms a substance which we call 

 mortar, or cement ; in proportion, therefore, as the quality of 

 these materials is more or less perfect, so does the substance 

 become more or less compact, hard, solid, and impervious: 

 such must be the condition of the soil ; and it is but reasonable 

 to suppose that a great part of the seed sown upon it must 

 perish.' 



It may indeed be alleged that the caustic action of quick- 

 lime can never be exerted to any great extent, as it attracts 

 fixed air too strongly not to become immediately slaked; but 

 its effects are found to be powerful even in that short period, 

 provided that it be promptly and intimately mixed with the 

 soil ; for though the land should contain an aljundance of vege- 

 table matter, yet if it has been injudiciously cropped, or in- 

 sufficiently manured, the lime will only add to its infertility. 



As the dust of quicklime is prejudicial to health, care should 

 be taken by those who spread it over the land to work upon 

 the windward side. Precaution should also be used, when it 

 is ploughed in immediately after being spread, to do so when 

 the soil is quite dry, as well also as to prevent the horses from 

 passing through any wet places when going to field; for 

 though the powder of dry lime, when in a caustic state, does 

 not take any apparent effect on the skin, and the hands of a 

 person who has wrought in it are not in the least injured, yet 



* 'All the experiments yet made render it probable that the food of plants, 

 as it is taken up from the soil, is imbibed by the extremities of the roots only ; 

 hence, as the extremities of the roots contain no visible opening, we may 

 conclude that the food which they imbibe must be in a state of solution at 

 first ; and, in fact, the carbonaceous matter in all active manures is in such a 

 state of combination as to be soluble in water whenever a beneficial effect is 

 obtained.'— L)r. Thomas Thomson's Chemistry, 3d edit., vol. V. p. 376. 

 n-Z 



