of Atmospheric Nitrogen and Oxygen by Water. 95 



stream downwards, as they are formed, with little or no 

 tendency to dissipation of their dissolved air-content in 

 lateral directions. 



For this experiment a double- bulbed tube of the form 

 shown in fig. 3 was employed. The two bulbs A and B 

 were of 175 c.c. capacity each. They were 

 Fig. 3. connected by a narrow tube C, 6*4 mm. bore and 

 300 mm. long. The lower bulb B terminated in 

 a small draw-off tube b, and the upper bulb A 

 was continued by the straight tube D, about 

 50 mm. long and 20 mm. bore. 



The whole tube was exhausted and filled with 

 sea-water, the dissolved gases in which had been 

 previously removed by boiling the water in vacuo, 

 and extracting the gases by means of the 

 mercury pump, described in Part I. of this 

 communication*. The tube after being filled was 

 securely closed from contact with the air, and 

 placed in a thermostat, kept at the temperature 

 of 12°-7 to 13° C. 



When the contents of the tube had attained 



the temperature of the thermostat, the cork was 



removed, and a little water was drawn out so as 



to lower the level of the water in the tube to 



about 20 mm. below the mouth of D. The tube 



was then fitted with a cork, furnished with outlet 



and inlet tubes, so that a small air space was left 



above the water in D, through which a current 



of air could be drawn without disturbing the 



surface of the water. Two weighed calcium 



chloride tubes were attached to the outlet tube, 



to absorb the water-vapour brought over from 



the water in the bulb with the air-current, and to afford the 



means of determining the weight of water evaporated during 



the experiment. 



A current of air, previously dried by passing through 

 calcium chloride tabes, was drawn through the air-space in 

 the tube for six days. The dissolved air-content of the water 

 in the upper and lower bulbs was then separately determined, 

 with the following results : — 



Gases expressed in c.c. at N.T.P. per 1000 c.c. sea-water. 



Upper Bulb. Lower Bulb. 



Oxygen 3*10 2*80 



Nitrogen 6'83 5'43 



* Phil. Mcig. Sept, 1919, p. 817. 



