Fiff. 3. 



Solution of Atmospheric Nitrogen and Oxygen by Water. 325 



The form of apparatus finally adopted is 

 shown in fig. 3. It consists of an inner 

 tube, about 1 metre long and 1 cm. bore. 

 Into each end of the tube a rubber stopper 

 is fitted. The lower stopper carries a small 

 Ctjpkf - I capillary stopcock, and the upper one, a two- 

 way stopcock, with capillary tubes. One 

 limb of this tap was cut off short, and inserted 

 in the stopper. Of the two other limbs one 

 was left straight, and cut off short, while the 

 other was bent over until parallel with the 

 long tube, and a length of fairly wide capillary 

 tubing was fused into it. The lower end of 

 this tube was connected by rubber tubing 

 with the movable limb of the manometer, 

 which was also provided with a stopcock, to 

 prevent the liquid spilling when inverted. 

 This manometer was filled with water, coloured 

 with a little methylene-blue. 



The long tube was completely surrounded 

 b}* an outer jacket, held in place by rubber 

 stoppers, which were provided with inlet and 

 outlet tubes for a current of water. 



A mark B was made on the manometer-tube 

 to which the level of the meniscus was always 

 brought when taking a reading, and the 

 volume of the space between this mark and 

 the stopcock was measured by filling with 

 mercury and weighing the mercury. This 

 small volume involved a constant correction, 

 which h;id to be applied to the observed 

 manometer readings in order to get the true 

 pressure in the tube. 



p' =loss in pressure in bubble, 



^> 1 = loss in pressure measured on manometer, 



v =. volume of capillary, 



V = volume of bubble, 

 then p' and p x are connected by the formula 



If 



r 



=j*(i+V> 



The experimental tube was filled with the air-free water 

 by exhausting it as completely as possible by means of a 

 water-pump, and then attaching it to the vessel containing 

 the air-free water. By opening the connecting tap. and 

 allowing air to flow into the vessel containing the supply of 

 distilled water, the tube was filled, almost completely, without 



