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to the tent, as the apparatus could not be used in a boat 

 except in a dead calm. Owing to these drawbacks, which 

 made themselves very keenly felt, when it became necessary to 

 travel quickly and to cut down the stays at most of the stations, 

 I endeavoured to simplify the method as much as possible. 



if you shake one liter of destilled water, at a temperature 

 of 15.6° by which the coefficient of absorption is 1, with 100 cc. 

 of air, free from carbonic acid, until equilibrium is attained, 

 then it is obvious that the tension of CO., in the water will 

 only be diminished by Vio of its value on account of the 

 carbonic acid given off to the air. If the coefficient of absorption 

 is higher, as is the case at lower temperatures, or if the 

 carbonic acid is not simply held in solution, but for the most 

 part present in dissociable combinations, the diminution of the 

 original tension will be even less. 



I therefore thought it probable that I might determine 

 without any appreciable error the tension in natural waters, 

 which nearly always contain the greater part of their carbonic 

 acid as bicarbonates, simply by shaking a sample of the water 

 with a much less volume of air and subsequently analyse the 

 air-sample for carbonic acid. 



In order to test this method I made the following 

 experiment: 



1. The COg- tension of a sample of seawater was deter- 

 mined by means of the tonometer and found = 0.02 "/o. 



2. 55 cc. of this water were shaken vigorously for five 

 minutes with 20 cc. of air. The quantity of carbonic acid 

 found in this air vas likewise = 0.02 %. 



3. 35 cc. of the water were shaken vigorously only for 

 one minute, with 40 cc. of air. The quantity of carbonic acid 

 in the air was = 0.02 %. 



4. 40 cc. of the water were shaken for about five minutes 

 as gently as possible — in such a way that the surface was 



