ACTION OF THE ATMOSPHEEE 



157 



Twenty-one tests of the air in various parts of Boston, during 

 tlie spring, 1870, showed the presence of 3.85 parts of carbonic 

 acid in 10,000. Eleven tests of the winter air in Cambridge 

 yielded 3.37 parts in 10,000.^ Dr. J. H. Kidder found the out- 

 door air of Washington to contain 3.87 to 4.48 parts in 10,000, 

 while Dr. Angus Smith, after an elaborate series of experiments, 

 reported the atmosphere of Manchester (England) as contain- 

 ing 4.42 parts in 10,000.^ 



These amounts are considerably in excess of those reported 

 by Miintz and Aubin,^ who give the following figures relative 

 to the proportional amounts in 10,000, as determined at the 

 various widely separated stations. The amount, it will be per- 

 ceived, is slightly greater during the night than during the day. 



Carbonic Acid in the Atmosphere 



Locality 



Hayti ...... 



Florida 



Martinique .... 



Mexico 



Santa Cruz, Patagonia . 

 Chubut, Patagonia . . 

 Chili 



Day 



2.704 



2.920 



2.897 



2.947 



2.735 



2.850 



2.665 



2.860 



2.664 



2.670 



2 790 



3.120 



2.665 



2.820 



Night 



The general mean is then 2.78 parts in 10,000, that for the 

 night alone being 2.82. For the north of France the mean is 

 given as 2.962, for the plain of Vincennes 2.84, and for the 

 summit of the Pic du Midi 2.86. 



Fischer, as quoted by Branner,* has shown that in rain and 

 snow water the amount of carbonic acid varies between 0.22% 

 and 0.45% by volume of water. Assuming that the mean of 

 these figures fairly represents the general average, it is easy, 

 knowing the rainfall of any region, to calculate the amount of 

 the gas thus annually brought to the surface. Professor Bran- 

 ner has thus calculated that from 3.21 to 11.80 millimetres of 

 carbonic acid (COo) are annually brought to the surface in cer- 

 tain parts of Brazil. The same method of calculation applied 



^ 2d Ann. Eep. Mass. State Board of Healthy 1871. 

 2 Air and Rain, p. 52. 



^Comptes Rendus, Yol. XCIII, 1881, p. 797 j also XCYI, 1883, pp. 

 1793-97. 

 *0p. cit. 



