70 PEINCIPLES OF GARDENING. [CH. II. 



are presented as supporting the theory. In the first 

 place, all waters contain earthy, saline, and organic 

 matters : even distilled water is not pure, as Sir H. 

 Davy has proved; and rain water, Margraaf has 

 demonstrated to be much less so. No plants, grow- 

 ing in water only, will ever perfect seed ; and the 

 facts, that different plants affect different soils, and 

 that a soil will not bear through a series of years the 

 same crop, whereas it will bear a rotation of different 

 ones, demonstrate that they each take different kinds 

 of food from the earth, and not that imiversal one, 

 water, which is ever present and renewed. 



So far, indeed, from water being the sole food of 

 plants, they are injured and destroyed by its super- 

 abundance in the soils sustaining them. Such soils 

 are always colder than well-drained soils, inasmuch 

 as that the same quantity of caloric which vdW heat 

 ^the earth four degrees, will only heat water one 

 degree — or, to use the language of the chemist, the 

 capacity for heat of water is four times gi'eater than 

 that of the earths. Secondly, the vegetable decom- 

 posing matters in a soil, where water is superabimd- 

 ant, give out carburetted hydrogen, acetic, gallic, 

 and other acids, instead of carbonic acid gas and 

 ammonia — products essential to healthy vegetation. 

 Palliatives for such evils are the application of lime, 

 or its carbonate (chalk), to the soils in which these 

 acids have been generated ; and indeed after they 



