Lerts & Bhake—TZhe Carbonic Anhydride of the Atmosphere. 191 
from which it would appear that the amount of atmospheric oxygen 
does perceptibly increase during the period of vegetable activity, 
and decrease when vegetation is dormant. 
Influence of Atmospheric Precipitates—(1) Fog and Mist. 
The first observer to draw attention to the influence of fog and 
mist on the amount of atmospheric carbonic anhydride was, we 
believe, Angus Smith. ? 
In his summary of the results of his examination of the air of 
Manchester he gives the figures :— 
During fogs, . i 5 : : 6°79 
Ordinary weather, . : ‘ : 4:03 
Since then, Russell? has published a series of investigations on 
the amount during London fogs, and has contrasted it with the 
quantity found under normal conditions. His experiments ex- 
tended from January, 1882, to April, 1884, during which period 
he recorded twenty-nine observations made in fogs of different 
degrees of density, and one hundred and thirty under normal con- 
ditions. His results may be summarised as follows :— 
Vols. Vols. 
of COs; ot COs; 
During Fogs. in Ordinary weather. in 
10,000 10,000 
air. air. 
Maximum, | Dec. 11th, 1882, 5 p.m. | 14:1 Oct. 28rd, 1882. Fine, | 6°4 
Thick, white fog, 
Minimum, | Oct. 10th, 1882, and Jan. 4-5 | Aug. 7th, 1882. Very fine | 3:0 
18th, 1884. Slight fog, (Bank Holiday), 
Mean, _. | (29 observations), . . | 7:2 | (130 observations), . - | 4:0 
The table he gives, showing several instances of the rapid 
1 Angus Smith, ‘‘ Air and Rain,”’ p. 52. 
Russell, (1) Monthly Weather Report of the Meteorological Office for April, 1884 5 
(2) Meteorological Council Report, ending March, 1884. 
