of the common Air at Sea. 361 
October 26th, the weather being very dark and rainy, 
I found that one meafure of common and one of nitrous 
air occupied 105. 
You know, sir, that the lituation of my lodgings was 
fuch, that the back part of the houfe was contiguous to 
the garden of Carleton Houfe, which is amply furnifhed 
with lofty elm trees, fo as to make the garden appear, 
from my windows like a foreft. As 1 had difcovered, in 
the courfe of laft fummer, the great power which the 
leaves of trees poffefs of improving the atmofphere, 
by pouring down an invisible fhower of purified or 
dephlogifticated air, during the day-time, in clear 
weather; I could not forbear afcribing in fome mea- 
fure the purity of the common air of that fpot to the 
happy lituation of the place juft by fo many trees, 
which had all kept their leaves in full vigour till 
that time. But I only give this as a conjecture ; for I 
am really forry that I cannot prove it by a direcft experi- 
ment. To put out of all controverfy fuch a powerful in- 
fluence of neighbouring trees upon the circumambient 
and unconfined air^, the air of different and diftant 
(c) I fay unconfinedy for I am not quite fure that the influence of trees and 
other vegetables, though in reality very great (as I think I have put beyond 
all doubt in my book) can be more fenfibie near trees in the open air than at 
feme diftance ; in the fame manner as fome diifilied water, poured gradually 
among an immenfe mafs of common water, would diHufe itfelf foon through 
the whole mafs equally. 
places 
