138 



light, and easily moveable. Spring water con tains 

 less ot it than river water, river water more than rain 

 water. 



To which of these waters, or the matter sustained 

 therein, do vegetables owe their growth ? In order to 

 decide this, the follow ing experiments were made. Se- 

 veral phials of the same shape and size were filled with 

 equal quantities of water. Over each was tied a piece 

 of parchment, with a hole in it just large enough for 

 the stem of the plant, to prevent the water from eva- 

 porating, or ascending any way but through the plant. 

 Several plants being exactly weighed, were then placed 

 in these phials, and as they imbibed the water, more 

 was added from time to time. Each glass was marked 

 with a different letter, and all set in the same window, 

 from July 20, till October 1. Then they were taken 

 out, the water in each phial weighed, and the plant 

 with the leaves that had fallen ofi It then appeared 

 how much each plant had gained, and how much water 

 had been expended upon it. 



li 

 it 



A. Spear-mint set in 

 spring- water. 



B. Spear-mint in rain- 



water. 



C. Spear - mint in 

 Thames, water. 



~ a 

 -S,*- 



27 



28 



28 



49 



D. Night, shade in 

 spdrig.water. 



The water ascends through the vessels of plants, as 

 through a fiitre. And a larger filtre draws more water 



