WATER. 



WATER. 



3708 grains, and a lathy rus of 98 grains j 

 emitted 2501 grains. 



In a previous page of this Encyclopaedia, I 

 have endeavoured to show the various uses of 

 the earths to vegetation. (See EARTHS.) The 

 cultivator will-observe how many of their chief 

 fertile properties are connected with their at- 

 traction for the aqueous vapour of' the atmo- 

 sphere, their powers of absorption, their capa- 

 bility of retaining it. It is in vain, indeed, by 

 any contrivance to attempt to make plants of 

 any description vegetate in absolutely dry earth, 

 or in air from which the aqueous vapour is en- 

 tirely withdrawn. It is true that some of the 

 flowering roots of the East, and some of the 

 mosses of our own country, almost appear to 

 do SQ; but such plants support themselves by 

 absorbing a certain degree of moisture, even 

 M'hen suspended, as in oriental countries, by a 

 silken cord from the ceiling of the room, or 

 from apparently dry brick walls; for when by 

 chemical means the moisture is entirely re- 

 moved from them, even these hardy plants 

 cease to vegetate." 



Various foreign substances have been sup- 

 posed to exist in minute proportions in rain- 

 water, to which its fertilizing effects have been 

 chiefly ascribed: thus ammonia is believed by 

 Professor Liebig to exist in rain-water. No- 

 thi-og, however, is more likely to lead to erro- 

 neous general conclusions than the detection 

 of minute foreign substances in water. Such 

 hasty generalizations have often deceived the 

 most excellent philosophers : thus the great 

 Boyle, by digesting pure water for a lengthen- 

 ed period in glass vessels hermetically sealed, 

 found that it deposited a minute quantity of 

 flint in powder; and hence he was led to con- 

 clude that water was in this way converted by 

 long boiling into silica, an error which several 

 other philosophers adopted, until the celebrated 

 Lavoisier and Dr. Priestley proved that the 

 flint deposited arose from the water having, by 

 long boiling, partially dissolved the glass. In 

 the same way even Davy, the most cautious 

 of experimentalists, once thought that chlorine 

 and soda might, by the influence of the voltaic 

 pile, be obtained from water absolutely pure; 

 but more careful and rigid experiments soon 

 convinced him of the extreme difficulty of pro- 

 curing entirely pure water, the vessels in which 

 the water was procured communicating, with 

 every apparent caution, sundry impurities ; and 

 this difficulty, I think it very likely, the skilful 

 chemists of Germany have not successfully 

 escaped. 



Water exists in all cultivated land in some 

 proportion or other. The quantity, however, 

 necessary to be present in the farmer's soils to 

 obtain the maximum advantage varies with 

 their nature, the climate, and the crop. For 

 instance, the rice-fields of India require a de- 

 gree of moisture which would be utterly de- 

 structive to the grain crops of the English far- 

 mer. The most porous, sandy land in a rainy 

 climate will be prolific, when the same soil in 

 a dry, warm country will be absolutely barren. 

 Even the drifting sands of Arabia, for instance, 

 if placed under the incessant rains of the Ame- 

 rican Andes, would certainly be speedily cover- 

 ed with vegetation. Some of the richest water- 



meadows of the south of England and of Scot- 

 land are formed on subsoils of broken flints, 

 gravels, and the roughest shingle. And, again, 

 the meadow-la-nds often need such copious sup- 

 plies of moisture as would be the means of de- 

 stroying the grain crops. The surface water 

 which tenants many uncultivated soils is. gene- 

 rally surcharged with a variety" of foreign sub- 

 stances, very commonly with vegetable mat- 

 ters. That in the gravelly soils is usually sur- 

 charged with oxide of iron; that resting on 

 calcareous .soils, with sulphate of lime (gyp-* 

 sum); whilst those from peat lands commonly 

 abound with sulphate of iron, or the red oxide 

 of the same metal. 



In most of the soils which the farmer has to 

 bring into cultivation, the removal of these wa- 

 ters is his first care; for such an abundance 

 of moisture is not only pernicious, from the 

 usual bad quality of the land water, but from 

 the quantity being far too great for the habits 

 of the plants which the farmer intends to cul- 

 tivate; such waters, too, dissolve, and some- 

 times carry off from the soil, in their imper- 

 ceptible drainage, all the soluble richest por- 

 tion of tfce soil. For many reasons, therefore, 

 draining has been long very justly held to be 

 the foundation of all agricultural improve- 

 ments; since its good effects are not confined 

 to the low marsh land, but its beneficial influ- 

 ence is extended to the most upland soHs. It 

 removes the land springs, and dries the sur- 

 face of thousands of acres of even the most 

 elevated of the English gravels. 



Almost to an equally beneficial extent has 

 the addition of water to plants for a lengthened 

 period been carried on by the cultivator in a 

 variety of modes ; by the gardener, either in 

 steam in his conservatories, or by the watering- 

 pot "in the open ground. Almost endless, in- 

 deed, are the varieties of artificial irrigation, 

 from the minor applications of the gardener to 

 the more gigantic efforts of the managers of 

 the water-meads. It is this branch of the in- 

 vestigation of the uses of water to vegetation 

 which is the most interesting to the farmer, 

 and to the head IRRIGATION I must refer the 

 reader. In regarding the uses of water to vege- 

 tation in this manner, however, the cultivator 

 must remember that it is not pure water that he 

 is thus using for his crops, but, as I have be- 

 fore remarked, water surcharged with a variety 

 of earthy, saline, and organic matters, to whose 

 presence a chief portion of the fertilizing effect 

 of such streams must be attributed ; for it is 

 found that the most foul and impure waters are 

 much the best for the purposes of irrigation: 

 thus the water of a river below a town is found 

 to be much more fertilizing than the sartie wa- 

 ter before it has been mixed with the contents 

 of the sewers. These are facts well known, 

 for instance, to the owners of the fine water 

 meadows of the valleys of the Itchen, the Ken- 

 net, and the Avon. That of the Thames above 

 the influence of the tide is not nearly so valua- 

 ble to the grazier as it is after it has had mixed 

 with its waters the huge mass of impure matters 

 from the London sewers. Then, again, by far 

 the richest irrigating waters, because the very 

 foulest of all, are those of the sewers of the 

 city of Edinburgh, which produce such singu- 



1095 



