WATER 



WATER. 



dustrious insects to change their habitation. ' 

 The nests of those wasps which build in the 

 earth may be destroyed with hot water or oil ; 

 those on trees are best suffocated by lighted 

 brimstone. (Kollar on Insects, p. 79.) 



Wasps are much affected by cold; so that 

 when winter begins to set in they become less 

 bold and savage, and they all perish, except a 

 few females, as soon as the frost begins. This 

 is a wise provision of nature ; for, did they 

 survive the winter, they would soon rival the 

 locust in their destructive depredations. 



WASTE LAND. The following is an ac- 

 count of the quantity of land uncultivated and 

 waste in the British dominions, including Scot- 

 land, Ireland, and the British islands, according 

 to the evidence of Mr. Cowling before the 

 Emigration Committee in 1827: 



WATER. A well-known, universally dif- 

 fused substance, which in ordinary tempera- 

 tures is fluid, but is solid when cooled down to 

 32 of Fahrenheit's thermometer. It rises into 

 vapour at all temperatures, even below the 

 freezing point, and at 212 expands suddenly 

 into steam. It is composed, by weight, of oxy- 

 gen 8 parts, and hydrogen 1 part. 



r is one of the most useful elements in 

 the arts and manufactures, as well as in rural 

 and domestic economy. The extensive utility 

 of wau-r for imparting motion tomachinery, and 

 for domestic purposes, is too well known to 

 require explanation; and as we have already 

 treated of its beneficial properties for irrigat- 

 ing land, under this head we shall have prin- 

 cipally to confine ourselves to its uses to 

 plants. 



Its r.v-.v to Vtzdation. The value of water to 

 vegetation very early attracted the attention of 

 mankind. In the most ancient of all books, 

 Genesis ii. 10, we are told that " a river went out 

 of Eden to water the garden." And the earliest 

 of the Greek and Egyptian philosophers, as- 

 tonished and confused by the magic effects 

 which water produced upon the rank and luxu- 

 riant lands of the warm eastern climates, were 

 loud in their praises of the unaided powers of 

 water to support vegetation. They not only 

 regarded it as one of the four elements of which 

 the world was composed, but Hippocrates con- 

 sidered it to be the substance which nourishes 

 and supports plants and animals. Theophras- 

 tus even considered that all metals were pro- 

 duced from water. The opinion that pure 

 water, and water only, was able to support 

 vegetation, was in succeeding ages long the 

 opinion of many philosophers distinguished 

 for their laborious investigations and their 

 ardent love of truth. Amongst these may be 

 named Van Helmont, Bonnet, Duhamel, Tillet, 

 and the illustrious Boyle. These great men 

 deceived themselves, however, by not suffi- 

 ciently attending to the purity of the water t 

 139 



with which they experimented,or guarding with 

 rigid accuracy against other sources of error. 

 Of the many researches which they instituted 

 to determine this point, none was more appa- 

 rently conclusive than that of the well-known 

 willow tree experiment of Van Helmont, which 

 long deceived, from its apparent accuracy, the 

 philosophers of that age. This celebrated ex- 

 perimentalist planted a willow which weighed 

 5 Ibs. in a common earthen vessel filled with 

 200 Ibs. of soil, which had been previously 

 thoroughly dried in an oven, and then moisten- 

 ed with only rain-water. This earthen vessel 

 he placed in the earth in a garden, covering it 

 over in such a manner that all access of dust, 

 &c., was prevented. For five years this willow 

 continued to grow, although moistened only 

 with either rain or distilled water. At the end 

 of that period, it was found to -weigh 169 Ibs., 

 although the earth in which it was planted, 

 when again dried and weighed, was found to 

 have lost only two ounces of its original weight. 

 Here, then, said the contemporaries of Van 

 Helmont, is an increase of 164 Ibs., and yet 

 the only food the willow had was water ; it is 

 evident, therefore, that pure water, and water 

 only, is quite sufficient to support vegetation. 



Various sources of error were, however 

 speedily discerned to prove that this experi- 

 ment was totally insufficient to decide this 

 question. The illustrious Bergman, in 1773, 

 showed that the rain-water employed by Van 

 Helmont, so far from being chemically pure, 

 contained sufficient earthy matters to supply 

 the whole of that found in the willow tree. 

 And, in addition to this, it was afterwards 

 shewn that unglazed earthen vessels readily 

 imbibe and transmit the moisture of the soil 

 in which they are placed : now this moisture 

 abounds with a variety of solid matters, both 

 organic, earthy, and saline. (Thomson, vol. iv. 

 p. 313.) 



Still more accurate experiments have been 

 since instituted with water chemically pure, with 

 very different results. In this way all attempts 

 to raise plants have in every instance totally 

 failed, although, as I have in another place 

 had occasion to remark, I have fruitlessly va- 

 ried the attempt in several ways. See LIQ.UID 

 MANURE. 



Although, however, it is, from tho result of 

 these laborious researches, pretty clearly 

 proved that water is not the sole food of plants, 

 yet it must be evident to the most casual ob- 

 server what an indispensable food this univer- 

 sal fluid is to vegetation. To all vegetation, in 

 fact, it is an indispensable necessary of life, 

 although almost every species of plant re- 

 quires to be supplied with it in varying pro- 

 portions : some, such as the aerial epidendron, 

 and pther Oriental plants, being able to supply 

 themselves from merely the aqueous portion 

 of it which always exists in the atmosphere; 

 while some, such as the rice plant, and the 

 aquatics, cannot prosper without being sup- 

 plied with it in such copious quantities as 

 would be destructive to the ordinary crops of 

 the farmer. In some proportion or other, how- 

 ever, they all require it, and all attempts have 

 been in vain made to cause plants to grow in 

 situations where moisture was absolutely 

 5 A 1105 



