WITH REFERENCE TO HORTICULTURE. 3 



of the current year ; and hence, also, they should be cultivated to 

 a greater depth than other soils, in order that there may be a greater 

 ma-* of material for retaining moisture. One great advantage of a 

 sandy soil over all others is its natural warmth. This arises from its 

 greater looseness and porosity, in consequence of which the atmosphere 

 penetrates into it more rapidly, and to a greater depth, than in the case 

 of any other soil. Hence, in the absence of sunshine, a sandy soil will 

 l)i' raised to the temperature of the atmosphere, to the depth of several 

 inches, by the mere penetration of the air among its particles ; while a 

 firm, compact soil, the earthy basis of which is clay or chalk, could not 

 be heated to the same depth without the direct influence of the sun's 

 rays. Sandy soils are also more easily penetrated by water than any 

 others, and hence they are sooner raised or lowered to the temperature 

 of the rains which fall on them than a clayey or calcareous soil. As 

 the water never rests on sandy soils, they are never cooled down by 

 evaporation ; the reverse of which is the case with clayey and calca- 

 reous surfaces. Sandy soils being % much less cohesive than soils in 

 which clay or lime prevails, they are much more easily laboured ; and 

 being always loose and friable on the surface, they are better adapted 

 for the germination of seeds. Sandy soils may be made to approach 

 alluvial soils by the addition of clay and calcareous earth, either taken 

 from clayey or calcareous surfaces, or from subsoils in which these 

 earths abound; but the former source is greatly preferable, from the 

 earths being already in combination with organic matter. 



Whatever has been said of sandy soils is applicable to gravelly soils ; 

 in some particulars in a greater, and in some in a less degree. The 

 small stones of which the greater part of gravel consists being better 

 conductors of heat than the particles of sand, it follows that gravels are 

 both more easily heated and more easily cooled than sands ; they are 

 also more readily penetrated by rain, and more readily dried by filtra- 

 tion and evaporation. Like sands, they are improved by the addition of 

 clay and chalk, or by alluvial soil ; and they require also to be culti- 

 vated to a greater depth than clays or chalks. A gravelly soil, isolated 

 so as not to be supplied with water from higher grounds, is of all others 

 the most suitable for a suburban villa (* Sub. Arch, and Landscape 

 Gard.,' p. 16); and therefore, though not so suitable for a kitchen- 

 garden as a sandy or loamy soil, yet as a sufficient portion of soil, what- 

 ever may be its earths, may always be improved so as to render it fit 

 for the cultivation of vegetables, a gravelly or sandy soil for building 

 on should never be rejected. 



Clayey Soil. Alumina, which is the basis of clayey soil, is the most 

 frequent of earths next to sand. It is found nearly pure in the ruby and 

 sapphire, tolerably so in the blue or London clay, but more so in the white 

 plastic clay which is found between the London clay and the upper chalk, 

 and which is used for making tobacco pipes. This soil, relatively to water, 

 is the very reverse of sand ; for while in nature sand and water are never 

 found chemically combined, in clay they are never found chemically sepa- 

 rate. Hence, though clay when prepared by the chemist, and kept apart 

 from water, appears as a light dry powder, scarcely different to the 



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