LIQUIDS AND ALLIED EXPERIMENTS. 



83 



63. Diffusion of Air into Air Through A1C1 3 Solution. — This is the 

 original solution of the series and nearly concentrated, the density being 

 p= 1.1550 at 19 , corresponding to 20.2 grams in 100 grams of solution or 

 25.3 grams in 100 grams of water. The vapor pressure, for want of specific 

 data, was taken the same as CaCL and is thus 7r' = 7r(i —0.177). 



Table 44. — Air into air through A1C1 3 solution (25.3 grams in 100 grams water). 

 Vessel A (single tube). Constants as in table 16. p u = 1.1550 at 19 . 



Date. 



Barom- 

 eter. 



t 



H i » 



Date. 



Barom- 

 eter. 



t 



H 



flu 



Dec. 26. . 



77.10 





 17.0 



7 1 . 46 1 4 . 92 i 



Jan. 3 . . 



73.98 





 17.9 



71.25 



4.892 



28.. 



75 -50 



17.0 



71.21 | 4 . 904 



10. . 



77-35 



•7-4 



70.95 



4.879 



30.. 



75-74 



17.2 



71.38 ! 4.912 



17. . 



76-54 



17. 1 



70.62 



4.861 



31. . 



76.34 



'7-5 



71.41 4.910 



24. . 



76. 10 



'7-4 



7045 



4.845 



Jan. 1 . . 



76.01 



17.7 



71.44 4.909 



31. . 



76.17 



'7-5 



70-34 



4.836 



2. . 



76.87 



17.8 



71.43 . 4.906 













AS~L 



2eb?6 



Fig. 36. — Chart showing loss of standard vol- 

 umes of gas in diver in lapse of days. 

 Diffusion of air through AICI3 solution. 



The record of results is contained in table 44 and fig. 36 and is largely 

 completed in weekly periods. The diffusion is slow and 

 reasonably regular, showing the rates 



n = 0.00225 c.c./day or io 10 k = 0.076 



a very low value in correspondence with the density of 

 solution. 



6 



,A 



ar\ 



7, 



h' 



64. Diffusion of a Gas Through a Manometer Tube. — 



This method of finding the coefficient of diffusion is neces- 

 sarily excessively slow. It was installed merely as a cor- 

 roboration of the above data for k, which it was supposed 

 to reproduce in order of value. 



In fig. 37, ab is a manometer tube about 0.6 cm. internal 

 diameter, closed at both ends and containing about the 

 same volume of air, ac and bd, at each end of the liquid cb. 

 In this way the effect of temperature is diminished, 

 though it is necessary to observe a nearly constant tem- 

 perature, since the liquid invariably expands. 



This tube with a thermometer was placed in a vault, to be observed in 

 the lapse of years, more than one of which has since gone by. The excur- 

 sion of the two ends of the liquid column are separately read off, c rising 

 and b falling by less than a millimeter in a year. Glass scales were attached 

 to the shanks of the tube for this purpose. 



Fig. 37. — Closed 

 manometer ad- 

 justed for diffu- 

 sion of air through 

 water. 



