Solution of A tmospheric Nitrogen and Oxygen by Water. 395 



by rubber tubing with the mercury reservoir E and the 

 tube G, respectively. 



The manipulation involved in an experiment was as 

 follows : — After the whole apparatus had been carefully 

 cleaned, the manometer was filled with water and the tube 

 filled with mercury by connecting on a temporary reservoir 

 at B ; at the same time the gas reservoir C was filled with 

 mercury by raising E. The water-level in D was also raised 

 to the hollow stopper, which was then turned so as to close 

 all the side tubes. The tube was then connected to the 

 boiling apparatus just described, by a capillary tube joined 

 to stopcock F. The air was displaced from this connexion 

 by forcing a little mercury over from the temporary reser- 

 voir. The water was then boiled until all the air was 

 extracted, when the water was displaced over into the 

 experimental tube, by lowering the reservoir of mercury 

 attached to it, and raising that attached to the laboratory 

 flask. 



When the tube was quite full it was disconnected from 

 the laboratory flask, and water from the thermostat was 

 circulated through the jacket until the required temperature 

 was attained. When a steady state was reached the stop- 

 cock F was connected to the reservoir of gas in use, and the 

 stopcock B to a standard burette, and the correct volume of 

 bubble drawn in. The gas reservoir C was then filled with 

 the gas by turning the stopper so as to connect it with the 

 bubble, and lowering the reservoir E ; the manometer space 

 was likewise filled by again turning the stopper and lowering 

 the manometer tube G. The tap at F was then disconnected 

 from the gas reservoir and opened and shut several times so 

 as to bring the manometer to zero and the pressure in the 

 bubble to that of the atmosphere. (The pressure in the 

 bubble before this operation was always slightly above 

 atmospheric, so that no air could enter.) 



The tube was then ready for the observations which were 

 made as usual after each double inversion. During the 

 inversion the stopper was turned so as to shut all side tubes, 

 and it was so arranged that after inversion the bubble could 

 be connected to the manometer alone, to read the pressure, 

 and then to the manometer and gas reservoir simultaneously, 

 to allow of the pressure being re-adjusted to atmospheric, by 

 manipulating the mercury reservoir E until the manometer 

 went back to zero. 



By means of this apparatus the difficulty about the 

 temperature and vapour-pressure of the replenishing gas was 

 overcome, because the gas was contained in the reservoir C 



