THE EARTH. 145 



earthy particles, is only the conveyer of such sub- 

 stances into the pores of vegetables, rather than 

 an increaser of them, by its own bulk : he also 

 shows, that water is ever found to afford so much 

 less nourishment, in proportion as it is purified 

 by distillation. A plant in distilled water will 

 not grow so fast as in water not distilled ; and if 

 the same be distilled three or four times over, the 

 plant will scarcely grow at all, or receive any 

 nourishment from it. So that water, as such, 

 does not seem the proper nourishment of vegeta- 

 bles, but only the vehicle thereof, which contains 

 the nutritious particles, and carries them through 

 all parts of the plant. Water, in its pure state, 

 may suffice to extend or swell the parts of a plant, 

 but affords vegetable matter in a moderate pro- 

 portion. 



However this be, it is agreed on all sides, that 

 water, such as we find it, is far from being a pure, 

 simple substance. The most genuine, we know, 

 is mixed with exhalations and dissolutions of vari- 

 ous kinds ; and no expedient that has been hither- 

 to discovered is capable of purifying it entirely. 

 If we filter and distil it a thousand times, accord- 

 ing to Boerhaave, it will still depose a sediment ; 

 and by repeating the process, we may evaporate 

 it entirely away, but can never totally remove its 

 impurities. Some, however, assert, that water, 

 properly distilled, will have no sediment;* and 

 that the little white speck which is found at the 

 bottom of the still, is a substance that enters from 



* Hill's History of Fossils. 

 VOL. I. K 



