118 HISTORY OF 



of heat could easily sepai'ate. Thus we see a body, extremely 

 fluid of itself, in some measure assuming a new nature, by being 

 united with otheis : we see a body, whose fluid and dissolving 

 qualities are so obvious, giving consistence and hardness to all 

 the substances of the earth. 



From considerations of this kind, Thales, and many of the 

 ancient philosophers, held that all things were made of water. 

 In order to confirm this opinion, Helmont made an experiment, 

 by divesting a quantity of earth of all its oils and salts, and then 

 putting this earth, so prepared, into an earthen pot, which no- 

 thing but rain-water could enter, and planting a willow therein ; 

 this vegetable, so planted, grew up to a considerable height and 

 bulk, merely from the accidental aspersion of rain water ; while 

 the earth, in which it was planted, received no sensible diminu- 

 tion. From this experiment, he concluded, that water was the 

 only nourishment of the vegetable tribe; and that vegetables, 

 being the nourishment of animals, all organized substances, there- 

 fore, owed their support and being only to water. But this has 

 been said by Woodward to be a mistake : for he shows, that 

 water being impregnated with earthy particles, is only the con- 

 veyer of such substances into the pores of vegetables, rather than 

 an increaser of them by its own bulk : and likewise, 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 sucli, 

 does not seem the proper nourishment of vegetables, 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 proportion. 



However this be, it is agreed on all sides, that water, such aa 

 we find it, is far from being a pure simple substance.* The 



* Water has been ascertained to be a compound substance, and its consti. 

 tiii-nts are clearly proved to be 85 parts of oxygen pas, and 15 of hydrog-eii 

 l.y \vei(,'lit.— M. Lavoisier has proved, that wlsen 85 parts of oxygen gas are 

 burned witli 15 of hydrogen gas, 100 parts of water are formed); and if 100 

 parts ot uatj>r are made to pass through a red hut iron tube, 15 parts of hy- 

 drogen gas vv II be procured, while the inside of the tube will be fooud coo. 

 v«rted into au oxyd, and to have gained S5 parts in weight 



