56 



THE DIFFUSION OF GASES THROUGH 



The tube gg is of use in charging the diver with gas. For this purpose 

 the apparatus A is inverted and then brought back to the erect position in 

 the figure so that the diver may be completely filled with the liquid. The 

 gas in question is then introduced in small bubbles through gg, while the 

 gas at H is kept about at the pressure (less than o. i atmosphere) at which 

 the experiment is to begin. When the diver rises the tube gg is closed. It 

 must subsequently be quite filled with the liquid by suction above, so that 

 there may be no accidental leakage of air from g to v. In fact, the tube g 

 may with advantage be straight. Gas may be led into v by tipping the 

 apparatus. Otherwise it escapes into II without charging the diver. 



Table 15. 



No. 



A.... 

 B.... 

 C... 

 E.... 

 F.... 

 H. ... 

 EE ... 

 FF... 

 K,SO, 

 BaCK 

 A.... 

 H .... 



.1/ 



12.01 1 



37-425 

 14.448 

 14.897 



23 -545 

 i 1.653 

 12.472 

 10.939 

 8.643 

 7.496 

 12.01 1 

 11.653 



Vessel. 



Tube. 



Pi 



2.484 

 2.470 

 2.487 

 2.466 

 2.466 

 2.466 

 2.466 

 2.466 

 2.466 

 2.466 

 2.484 

 2.466 



15.2 

 26.4 

 16.6 

 '7-3 

 17-3 

 17.0 



17-3 

 17 3 



"7-3 

 '7-3 

 15.2 

 17.0 



45 



9-3 



Float. 



7-8 



5-6 



6-7 



1 1-12 



1 1— 12 



7-9 



4-5-5- 



6-7 



6-7 



5-6 



7-8 



7-9 



When relative results only are in question, as, for instance, when different 

 strengths of a given solution are compared with water, the simpler appa- 

 ratus with a single tube is preferable. It is virtually standardized with 

 water at the beginning or end of the experiments. Unfortunately, in the 

 earlier part of the experiments the temperature difficulty was still encoun- 

 tered in the following work, there being no chamber of constant temperature 

 available. Later such a chamber was improvised. 



The constants of the floats used in the present chapter are given in 

 table 15. 



The divers were usually cut from test tubes and matched with regard to 

 the area of their mouths with the area of the stand glasses, in order to make 

 the area of the float and the annular area outside of it as nearly as possible 

 the same. The tubes should be of relatively heavy glass, so as to insure a 

 low position of the free surface within, permanently in the cylindrical part 

 of the test-tube. Otherwise the free surface is liable to contract into the 

 spherical part at the end, and a correction for this diminution of area is 

 difficult. 



