Lerts & Bhaxe—TZhe Carbonic Anhydride of the Atmosphere. 195 
The observations naturally fall into two groups—(a) town, 
and (4) country fogs, respectively. As regards the first of theses 
London fogs appear to be pre-eminent for the extraordinary pro- 
portion of carbonic anhydride they contain, and those of Manchester 
are not far behind them, it would seem. 
The fogs of continental towns show a remarkable difference in 
this respect—clearly seen in the case of Liége (where the observa- 
tions extended over a long period)—and the conditions as regards 
intensity of manufacturing operations would, we presume, be com- 
parable with those of Manchester. Paris, perhaps, should be 
ignored, as only two fog observations are recorded in Miintz and 
Aubin’s work, and the total number of observations is small. 
Buda-Pesth is at the foot of the list for towns, and practically 
no difference in atmospheric carbonic anhydride can be traced 
there to fog. 
Coming now to the country, we still find that fog or mist causes 
an increase, but the extent of this increase as might be expected is 
very different from that found in towns. The effect, however, is 
apparent, but from the table, at all events, its magnitude would 
appear to diminish as the sea coast is left and inland districts are 
reached. 
(2) Rain and Snow. 
The precipitation of rain, snow, &e., has been considered by 
many observers to exercise an important influence on the amount 
of atmospheric carbonic anhydride. 
Thus De Saussure says :—‘‘ One of the causes which has most 
influence on the variations of carbonic anhydride in different 
seasons, or in the same seasons of different years, is the accidental 
humectation of the soil by rain which probably diminishes this gas 
either by absorbing it or by causing the earth to absorb it. In 
order to judge of the influence of rain, it is necessary to compare 
in summer or autumn a season or a month of drought with a rainy 
season or month. Insignificant results are obtained by comparing 
two or three consecutive days without rain with two or three rainy 
days; rain acts but slowly on the air; a strong shower (averse), 
after a dry season, does not appear to immediately diminish the 
carbonic anhydride. . . . The action of rain does not appear 
able to make itself manifest in winter or spring in the climate of 
