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THE FARMER'S MAGAZINE. 



application of sandy and shelly marls to heavier soils ; 

 but ail these substances have been found useful on any 

 soils, where judiciously applied. 



Marls are often made into composts vfith earths and 

 farmyard dung, either in layers in the heaps, or in the 

 bottonDS of the cattle-yards, where it will be soaked by 

 the urinary fseces, and afterv/ards mixed with the mass. 

 It is thought that such a preparation is more efifectual 

 than marl by itself. Frequency of marling may pro- 

 duce a hurtful looseness in the land, which is very easily 

 removed by pasturing the land in rest for some years. 

 The avaricious use of the plough has produced the tri- 

 vial hurtful effects that have been observed from the 

 use of marls. 



The action of marls is usually attributed to the quan- 

 tity of calcareous matter which they contain, and to the 

 change that is made in the land by a mechanical action, 

 and a mucilaginous matter that is derived from the 

 esuvise of animcls. The extremely minute blending of 

 the ingredients of marl has been supposed to constitute 

 the fertilizing quality, each particle having the power of 

 exerting its peculiar property on the soil and on each 

 other, and of retaining or giving out the substances they 

 may form, that are favourable to vegetation, by the 

 different agencies and combinations. The clays impart 

 moisture to the sandy parts, and the land prevents the 

 clay from being too adhesive ; and thus the respective 

 qualities are exerted advantageously on each other. An 

 oleaginous nature has been discovered in its composi- 

 tion, arising from the mixture of the substances with 

 animal and vegetable matters ; and to this property 

 much of the fertility which it produces has been 

 ascribed. It is also thought to be an absorbent earth, 

 composed of clay and limestone, and that the useful 

 quality is derived from the very ultimate mixture of 

 these valuable ingredients. 



The quantity of calcareous matter is no certain cri- 

 terion either of the quality or effect of any substance. 

 A mineral acid will show the presence of calcareous 

 matter, but aflfords no directions either of the general 

 quality of the substance as a fertilizer, or of the quantity 

 that will be required to produce a result. The quan- 

 tity of calcareous matter is no certain criterion either of 

 the quality or the effect, for the marls that effervesce 

 little or none by the application of an acid are good ma- 

 nures ; and marls of great difference in colour, and in 

 chemical composition, have been dug from the same pit, 

 where they luy contiguous, and almost mixed with each 

 other, and have shown no discernible difference of ef- 

 fect on any crop when applied in equal quantities on 

 the same land. On coarse, heathy pastures, an appli- 

 cation of marl produces the usual effect of calcareous 

 matters, in banishing the rough faggage and substituting 

 a close sward of finer grasses. This result will be ob- 

 tained by the use of any substance, provided it be pro- 

 perly prepared for the intended purpose. 



Marls exposed for years retain the same properties as 

 when newly dug ; do not effervesce after calcination ; 

 and good ndarls feel greasy when touched, and friable 

 vvhen dry. If the land is generally good in quality that 

 lies on a bod of marl, the red and blue colours with 

 yellow veins are found to be the best in quality. Marls 

 are known by breaking into small pieces from ex- 

 posure, by the crackling of the particles of dry marl, 

 like salt, in the fire, and by throwing up bubbles to the 

 surface of the water by which it is covered, and by gra- 

 dually dissolving and forming with the water a soapy 

 substance, like a paste, and not unfrequently of a liquid 

 nature, the marl remaining dissolved and suspended in 

 the water without any coagulation. But water alone 

 vyill produce bubbles, when poured on certain dry clays 

 — thence it is recommended to subject clays to water for 

 a time before being tested by an acid. Marl contains 



no alkaline salt, as it imparts no quality, smell, or 

 taste when digested or boiled, and has nothing that is 

 soluble in water. Muriatic acid maybe applied till the 

 effervescence ceases ; the loss of weight will show the 

 quantity of air expelled, and the recoainder is earth. 

 The quantity of calcareous earths may be ascertained by 

 dissolving the marl in muriatic acid, diluting the liquid 

 with water, passing it through a filtering paper, and 

 then precipitating the calcareous earths from tbe clear 

 liquid by a solution from some fixed alkaline salts. 



Marl is a heavy body, and being used in the crude 

 state, it is not, like lime, lightened by incinera- 

 tion, and rendered more conveniently portable. It is, in 

 consequence, only capable of being used in the vicinity of 

 the localities where it is found, and where two journeys 

 can be performed in a day. Reckoning on this incon- 

 venience, the cost per acre of top-dressing cannot be 

 stated below £4, and in most cases it will be above that 

 figure. But, on the other hand, the advantages from 

 the application are amply sufficient to repay that amount 

 of expense, in raising a much increased herbage of sweet 

 grasses, which lasts for several years ; in very greatly 

 improving the testimony of light sandy lands, by con- 

 solidating the materials ; and by attracting moisture and 

 by bringing forward on grass-lands, and maintaining, 

 a thickly-matted quantity cf grassy herbage to afford 

 nutriment to the following crops by the future decom- 

 position. On all grass-lands that are intended to be 

 ploughed for crops, the top-dressing must be applied at 

 least one year previous to the laud being broken up, in 

 order that the vegetable food may be provided by the 

 effects of the marl on the surface. This point is very 

 generally neglected. 



It has been very plausibly conjectured that marls are 

 a natural compost, formed of calcareous and other mat- 

 ters, and that the fertilizing property consists in the 

 very minute blending of the particles, which almost es- 

 cape detection by the microscope. This supposition 

 very strongly confirms our earnest recommendation that 

 all earthly composts be very finely pulverized, in order 

 that the comminuted intermixture of the ingredients 

 may yield the reciprocal action of the ultimate elements 

 of matter. An idea gathered from nature not only 

 strengthens and brightens experience, but advances the 

 theory and ennobles the art. 



No. 11.— Chalk. 



Chalk is a calcareous earth, and the most recent 

 stratified formation of the carbonate of lime. It is di- 

 vided into hard and soft chalk, and rests on the third 

 sand-stone formation ; it effervesces strongly with acids, 

 and is distinguished from magnesia by not being dis- 

 turbed by the caustic volatile alkali. Specific gravity 

 2.226, 2.252, 2.316, 2.657. Contains 



Lime 56.5 or 53 



Carbonic acid 43.0 or 42 



Water 0.5 or 3 



Alumina 2 



100.0 100 

 Hard chalk is burned into lime for building purposes; 

 and soft chalks are used in top-dressing arable and 

 grass lands, as clover leys, stubbles intended for wheat, 

 and on bare summer fallows. It must be dug from the 

 pits in autumn, and laid at once on the land that is to be 

 dressed. The raihs and frosts will be useful in pulveriz- 

 ing it, and what is left unreduced must be broken by 

 means of axes and hammers. Some attention is re- 

 quired in getting chalk properly pulverized. The fat 

 unctuous kinds soon crumble on exposure, but the 

 harder sorts require longer time and much labour. The 

 quantity laid on an acre varies much, according to local 

 circumstances. A medium may be stated at 40 to 50 



