Letts & Bhake— The Carbonic Anhydride of the Atmosphere. 198 
action of plants, or of masses of organic matter in a state of 
decomposition.” 
In commenting on the work of Reiset and of Mintz and Aubin, 
Dumas goes so far as to say—“ Laseule cause que semble propre a 
faire varier la quantité géologique d’acide carbonique de l’atmo- 
sphére consiste dans la formation du brouillard. La vapeur d’eau en 
se condensant, ramasse Vacide carbonique, et Vair brumeuse se 
montre généralement plus chargé de ce gaz que lair ordinaire.”’ 
It seems to us that foggy weather ought to occasion an in- 
crease in the amount of atmospheric carbonic anhydride, for the 
following reasons :— 
A fog, or mist, usually occurs during an anti-cyclonic period, 
when the conditions are a complete calm and a gentle SeNweaS aoe. 
flow of air from the upper regions. 
Emanations of carbonic anhydride, either from the soil or from 
the smoke of fires, are thus kept stationary, or are even depressed, 
and an accumulation of the gas occurs—very possibly this is aided 
by the screen of minute water-drops forming the mist or fog, 
which may prevent diffusion, and even dissolve the carbonic 
anhydride. 
We have collected in the following table a number of determi- 
nations bearing on the effects of fog and mist on the amount of 
atmospheric carbonic anhydride :— 
