PERSPIEATION. 



he planted a sunflower three and a half feet high in a garden 

 pot, which he covered with thin milled lead, cementing all the 

 joints so that no vapour could escape except through the sides 



Pig. XIV.— Halos's exporiment to determine the amount of poi-apiration. 



of the pot and through the plant itself; but providing an 

 aperture, capable of being stopped, through which the earth in 

 the pot could be watered. After fifteen days, viz., from July 3 

 to August 8, he found, upon making all necessary allowances 

 for waste, that this sunflower plant, three feet and a half high, 



