AND RURAL ECONOMIST. 313 



be overlooked by the most careless observer, while he saw 

 innumerable instances in which p'ants wither and dry for 

 want of this substance. But while this universal agency has 

 been acknowledged, it is believed that a very inferior office 

 has been assigned to it from that which it really performs. 

 It has been consid'^red as the mere vehicle which carried and 

 deposited the nutritious particles of other substances, while 

 it in reality was contributing much the largest portion of 

 the actual nourishment to the plants which annually clothe 

 our earth in living green. 



If this idea is correct, then he who possesses water at his 

 command with which to supply his plants at pleasure, or 

 who has a soil adapted to attract and retain moisture in 

 suitable quantities, possesses a mine of inexhaustible wealth, 

 from which he can draw at pleasure, in proportion to his 

 industry and his wants. 



In proof of the abstract principle that water constitutes in 

 a very large proportion the food of plants, I may be allowed 

 to mention one or two accurate experiments of distinguisli.ed 

 philosophers upon tlii subject, which appear to me to be 

 quite decisive on the case. 



' Mr. Boyle dried in an oven a quantity of earth proper 

 for vegetation, and after carefully weighing it, planted in it 

 the seed of a gourd ; he watered it with pure rain water, and 

 it produced a plant which weighed fourteen pounds, though 

 the earth producing ii had suffered no sensible diminution.' 



' A willow tree was planted by Van Helmont in a pot, 

 containing a thousand pounds of earih. This plant was 

 watered with distilled water or pure rain water ; and the 

 vessel so covered as to exclude all solid matter. At the end 

 of five years, upon taking out the plant, he found it had in- 

 creased in weight one hundred and nineteen pounds, though 

 the earth had lost only two ounces of its original weight.' 



The experiments of Mr. Cavendish and Dr. Priestley have 

 sufficiently proved that vegetables have the power of decom- 

 posing water and converting it into such fluids as they need 

 for circulation in their own vessels ; and that thev elaborate 

 from this substanQe such juices and fruits as they are by 

 nature calculated to produce. 



The grei' effect which is so frequently observed to follow 

 the formation of ditches from the road-sides on to mowing- 

 ground, is, no doubt, in part, to be attributed to the manure 

 which is thereby washed on to the ground, but is also in part 

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