100 



FARMERS' REGISTER. 



[No. 2 



mica! action, bat the strongest proofs of its having 

 taken place. The case belbre us, is therelbre, no 

 more than one of a large class in chenoistry, where 

 it is necessary to apply a chemical agent much di- 

 luted at first, while, alter the action has once com- 

 menced, the strength of the agent may be gra- 

 dually increased with advantage; and in the same 

 way, upon poor and exhausted soils, a large dose 

 of calcareous matter may produce no benefit, or 

 even positive injury, while a lighter dressing may 

 produce immediate good eflects, and prepare the 

 soil to receive with advantage, larger quantities, 

 The addition of putrescent manures, enables the 

 Jands to receive a larger dose of lime even from 

 Ithe first, and the successive dressings may in like 

 manner be increased if green crops are ploughed 

 in, or stable manure added. This is also consis- 

 tent with theory, for the surplus lime may be ad- 

 vantagoouslyemployed in absorbing the gases ge- 

 nerated by the decomposition. Still these are facts 

 that, although we may explain them in conformi- 

 ty with cheniical principles, could not readily have 

 been predicted before hand. 



One curious fact was observed by JMr. Rufiin, 

 in his chemical analyses of the soils of Virginia^ 

 namely, that even in regions where the rock, by 

 whose decomposition the soil was formed, was 

 limestone, not only did no carbonate of lime mani- 

 fest itself by effervescence with acids, but no pre- 

 cipitate was formed by the tests of lime in the 

 acid solution. He could not admit that, in such 

 soils, lime was absolutely wanting, and therelbre 

 inferred, that it was in such a state of combina- 

 tion, as to be neither soluble in waier, or decom- 

 posable by nitric acid. Such a combination is the 

 oxalate of lime, but as he has made no du'ect in- 

 quiry into its presence, and some of his correspond- 

 ents have questioned the probability of such an 

 union existing, he has, with the true spirit of an 

 inductive inquirer, modified his assertion until 

 ikriher proof be obtained. We, however, do not 

 think that so much modesty Avas necessary, for it 

 can be shown that the formation of oxalic acid, 

 and its consequent combination by superior affinity 

 with lime, whatever may be its previous stale of 

 combination, are at least probable, if not certain. 



The formation of nhric acid in calcareous soils, 

 by the absorption of its two elements from the at- 

 mosphere, is not only rendered probable by the 

 presence of nitre and nitrate of lime in the soils of 

 many warm countries, but made certain by the 

 construction of ' artificial nitre beds in France, 

 when the foreign supply was cut off by the pre- 

 ponderance of the British navy. When this acid 

 is formed in a soil abounding with vegetable mat- 

 ter, not yet decomposed, as is the case with many 

 of our newly opened regions, oxalic acid must be 

 formed. 



Such then are the properties of lime, considered 

 as a constituent of the soil: to bring its texture to 

 that best suited for tillage, and (()r conveying the 

 moisture, which is the vehicle of the food of plants, 

 neither in excess or in deli'ct; to condense and 

 ptore up that gaseous food until needed; to promote 

 the decomposition of inert organic matter; to neu- 

 tralize acidily, and coimteract its antiseptic action, 

 thus removing a noxious principle, and opening a 

 new supply of vegetable food. 



One other use of lime in soils remains to be 

 mentioned, and this does not seem to have oc- 

 curred to Mr. Ruffin, but is strongly urged by M, 



Puvis, in a passage we have quoted. The ashse 

 of all plants, when lixiviated, are composed ciihre 

 of the pure earths or earthy salts; of the latter, 

 those of lime are by liir the greatest in quantity, 

 although probably altered by the fire from their 

 original state. Thus, wood ashes contain the car- 

 bonate, suljihate, and p-hosphate of lime. In ad» 

 dilion, the liquor by which the alkaline matter is 

 separated by lixivialion carries with it earthy mat- 

 ter, which is rendered soluble by the alkali. Now 

 it cannot be doubted, that if this alkaline, earthy 

 and saline niatter is not contained in the soil, the 

 plant must be stinted iii its growth or actually die. 

 Thus to many plants, lime, or some of its com- 

 pounds, Ibrmsan essential article of ibod; it may 

 be required in less quantity than carbon, hydro- 

 gen, oxygen, and water, but is not the less neces- 

 sary to their growth. Now, former analyses did 

 not show that lime and its compounds are con- 

 tained in the stalks and seeds of the cereal gra- 

 mina; but the existence of earthy matter, undis- 

 solved by water or alcohol, or left as a rediduum of 

 combustion, was well known. More recent in- 

 vestigations have shown, that lime is one of the 

 constituents of this residuum. Silex certainly ex- 

 ists in the stalks, and particularly at the joints of 

 the gramina, being in some actually visible to the 

 naked eye. 



It is upon the same principle only, namely, that 

 it serves as the ibod ol" plants, that we can ac- 

 count for the efi'ects of gypsum upon certain 

 crops, which, in any other mode of viewing them, 

 would appear miraculous. This sulphate of lime, 

 if merely ground, has no attraction for moisture, 

 and, if burnt, would rather absorb it from the 

 soil than the air; it cannot therelbre act. as some 

 hav'e supposed, to increase the deposite of dew ; 

 it is so sparingly soluble in water, and so inert, 

 that it cannot act as a stimulus, nor is it certainly 

 followed by exhaustion, as all stimuli must he. 

 But althouglx sparingly soluble, it is still conveyed 

 by water, into the bodies of plants, although in 

 small quantities, and as that water undergoes the 

 chemical changes, which we know are induced by 

 the vital action of plants, the sulphate of lime 

 must be deposited in them, injuriously perhaps to 

 some, but as a necessary food to others. Thus, 

 it has been found that the ashes of clover, 

 lucern, and many of those plants whose growth 

 is known to be most certainly promoted by 

 gypsum, uniformly contain sulphate of lime ; 

 it is, therefore, their essential and appropriate 

 food. Some soils may contain it naturally — 

 here an addition will not increase the crop 

 of such plants; some may contain a substance 

 which will decompose the sulphate, and thus pre- 

 vent its action. The earth baryta will separate 

 the sulphuric acid from lime, and thus may produce 

 this effect; but this is so rare, that injury from 

 this cause can hardly be anticipated. Oxalic acid 

 will separate the lime from the sulphuric acid, and 

 thus will not only render the application of gypsum 

 inellicient, but will also set the acid liee to act in- 

 juriousl3^ But if the oxalic acid has been previ- 

 ously neutralized by lime, the sulphate remains 

 unaltered, and is capable of aiding the growth of 

 clover and other plants of the sort. In confirma- 

 tion of this view of the subject, we may quote the 

 experience of Mr. Rulfin. His soil would not 

 produce clover, even with the aid of plaster; and 

 this being known, ho did not attempt to use it, un- 



