252 Mr. Farey's Notes on Mr. Bakewell's Geology. 
combinations, were not restored to it again, the air would soon 
become unfit for the supporting of animal and vegetable life, 
And if the thermogen which enters the animal system, by means 
of the lungs, were not conveyed out of the body as fast as it is 
received, this invisible element would be constantly accumulating 
till it put a total stop to all the animal functions. 
As, neither thermogen nor photogen can be annihilated, we 
may infer, that the thermogen which is taken into the blood, 
after having entered into new combinations and passed through 
the animal system, flies off from the surface of the skin in com- 
bination with photogen. When this compound comes into the 
atmosphere, the thermogen is converted into oxygen gas by 
uniting with the moisture contained in the air; and the photo- 
gen, by the same means, becomes hydrogen gas, and ascends to 
the upper regions of the atmosphere, from whence it descends to 
the earth in a manner which will be described in some future 
communication. ; 
The following facts are sufficient to show in the most satis~ 
factory manner, that a strong attraction obtains between ther- 
mogen and moisture. : 
he electric machine never acts so well in a moist atmosphere 
as in a dry one, because the moisture attracts the thermogen 
(positive electricity). from the apparatus, and prevents its accu- 
mulation, And we experience more cold in a damp atmosphere, 
the thermometer being at 40°, than when the air is dry, though 
the thermometer, may be as low as 25°. The reason is evident : 
the moisture in the air attracts the thermogen from the animal 
system faster than it is supplied by the lungs. 
To Messrs. Nicholson and Tilloch. Ez. WALKER. 
[To be continued. | 
LIV. Notes and Observations on the Tenth and Part of the 
Eleventh Chapters of Mr. Roserr BakEwELv’s “ Intro- 
duction to Geology ;’’—embracing incidentally, several new 
Points of Geological Investigation and Theory, By Mr. 
Jouw Farry, Sen., Mineral Surveyor. 
[Continued from p. 190.] 
Notes, &c. 
P. 231, 1. 23, agitation of the waters *.—* A paper of Sir James 
Hall’s, just printed in the Edin. Trans., treats very fully on 
this subject. 4 
252, 1.25, artificial tarras*.—* The (late patent Cement of 
Parker, is made from the Clay-balls or Ludus Helmontii 
found in the London Clay, Rep. i. p. 111: a superior arti- 
By é. cle 
