INORGANIC MANURES. 



297 



the particles of adjacent bodies, and consequently 

 produces combinations, and facilitates reciprocal 

 unions. The winter will chill the operations, 

 and at that time there is no growing crop to de- 

 rive any present benefit." And in regard to the 

 condition of the soil, when lime is to be applied, 

 the same authority remarks, " Lime being re- 

 duced to a finely pulverised state by calcination, 

 it requires the soil to be, if possible, equally well 

 prepared with itself; for between a variety of 

 finely-blended ingredients there will be pro- 

 duced a number of reciprocal actions and afii- 

 nities of the different parts, that would not hap- 

 pen iu a smaller quantity of these substances in 

 a more aggregated and cohesive state." Besides, 

 as a manure, lime is useful iu all garden soils 

 which contain, to a greater or less extent, snails, 

 slugs, and insects, constantly preying on the 

 crops cultivated. 



An opinion has long existed against the use of 

 lime containing magnesia. " Such Mme," says 

 Mr Edward Solly, " is in general objectionable 

 as a manure. It is probable that the tendency 

 which magnesia has to remain caustic for a long 

 time, absorbing carbonic acid but slowly from 

 the air, is the cause of this." Magnesian lime- 

 stone, though it has been foimd to injure crops, 

 has yet been used with good effect in some cases. 

 " When a magnesian limestone is burned, the 

 magnesia is deprived of carbonic acid much sooner 

 than the lime ; and if there is not much vegetable 

 or animal matter in the soU, to supply by its de- 

 composition carbonic acid, the magnesia will 

 remain for a long while in the caustic state, in 

 which state it acts as a poison to certain vege- 

 tables." — Encyc. of Gard., p. 490. On the other 

 hand, Mr Donaldson, from his own practical ex- 

 perience, says, " On one field a double allowance, 

 or 400 bushels to an acre, was appHed as an ex- 

 periment to test the noxious quality of the lime. 

 In every case the application was attended with 

 the very best success, and for several years the 

 green and cuhniferous crops were excellent ; and 

 on the gi'ound where the double allowance was 

 appUed, the crops showed a great superiority. 

 Here was no damage from magnesian Ume, but 

 very great benefit." Different kinds of lime no 

 doubt produce different effects, but that none 

 produce the injurious effect noted above is, we 

 think, more than probable. Limestone rocks 

 containing alumina and silica produce a poorer 

 lime than pure limestone, but it is only their 

 poverty in calcareous matter that renders them 

 less valuable, and certainly no noxious quality 

 to affect vegetation exists in them. 



Clialh is a calcareous formation, supposed to be 

 composed, according to recent microscopical ob- 

 servations, of animalcules so exceedingly minute 

 that one cubic inch of it contains upwards of a 

 million of them. It is of three kinds — hard 

 chalk, Bofb chalk, and chalk marl. Hard chalk 

 is burned, and used in the same way as lime ; 

 soft chalk is dug from pits, and when spread on 

 the surface of the ground falls into a fine powder, 

 and is then readily incorporated with the soil. 

 Chalk marl is not very abundant, and when 

 found it is used in much the same way as the last. 

 As a manure, chalk acts much in the same way 

 as lime, only it is considered much less powerful 



in its effects. It also acts mechanically on soils, 

 rendering strong clays more easily worked, cor- 

 recting acidity in sour lands, and retaining mois- 

 ture in such as are very light, burning, or sandy. 

 Like shells and shell sand, it is useful to soils 

 naturally deficient in calcareous matter. 



Sulphate of lime or gypsum is also a calcareous 

 formation, or limestone in combination with sul- 

 phuric acid. It is useful in soils deficient in 

 calcareous matter, and to some extent absorbs 

 the ammonia from the air, and yields it to plants 

 in greater abundance than they could otherwise 

 obtain it. 



Phosphate of lime forms a constituent in almost 

 all plants, therefore its presence in any matter, 

 or iu its native pure state, is useful as a manure. 

 It is present in excrementitious substances, and 

 to a considerable extent in the straw forming 

 farmyard dung, and is a combination of phos- 

 phoric acid and lime. 



Nitrate of potass, which is the chemical name 

 of nitre or saltpetre, when reduced to a powder 

 by bruising, and applied during wet weather as 

 a top-dressing at the rate of one or two cwt. to 

 the acre, appears to act beneficially on loams and 

 clays, and the reverse on light sandy soils. 



Nitrate of soda, a compound of fossil alkali, is 

 ' soda combined with nitiic acid. It is used in the 

 same manner as the last, and thought by some 

 equal to it in affording nourishment to plants. 



It has been remarked by Mr Solly, in " Rural 

 Chemistry," p. 146, that " the nature of the in- 

 fluence which nitrates exert in vegetation is but 

 little understood. Some plants, such as the sun- 

 flower, tobacco, lettuce, and many others, always 

 contain more or less of these salts. Others do 

 not contain them, but, when supplied with 

 nitrates, are subsequently found to contain the 

 base without the acid. The soda, potash, or 

 lime is combined with some organic acid, whilst 

 the nitric acid has disappeared. It is probable 

 that, in these cases, the nitrogen of the acid is 

 assimilated by the plant, or that it assists in the 

 formation of gluten and alburnum. Nitrates 

 can have but very little value as manures on the 

 soils which naturally contain salts of nitric acid, 

 or which, in consequence of the substances they 

 contain, are constantly forming nitrates. On 

 soils containing neither nitrates nor other alka- 

 line salts, they appear to produce very beneficial 

 effects. These remarks apply equally to nitrate 

 of soda and nitrate of potash ; at least similar 

 effects are produced by the two salts as far as 

 regards the increased formation of gluten and 

 alburnum." 



Common salt is a combination of soda with 

 muriatic acid. This, with several other saline 

 substances, has been long employed as a manure, 

 and the results have been as various as the ap- 

 plications themselves. It is employed, no doubt, 

 with marked advantage to plants, natives of the 

 sea-coast, such as asparagus, sea-kale, &c., and 

 in such cases is applied by sowing it on the sur- 

 face previous to rain, and at the rate of from 16 

 to 20 bushels per acre, this being repeated two 

 or three times during the year. Salt is found in 

 every animal and vegetable manure. It is de- 

 tected in many plants, and consequently is of 

 advantage in stimulating vegetable growth, as 



