LIQUIDS AXD ALLIED EXPERIMENTS. 



83 



63. Diffusion of Air into Air Through AlCL 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 CaCU and is thus 7r' = 7r(i —0.177). 



Table 44. — Air into air through AICI3 solution (25.3 grams in 100 grams water). 

 Vessel A (single tube). Constants as in tatale 16. Pii = 1.1550 at 19°. 



?fl 



4Sj=. 



3tecZ6 51 Jan 5 It 



IS 



iS w 



OA 



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

 umes of gas in diver in lapse of days. 

 Diffusion of air through AlClj 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 



Z)q =0.00225 c.c. day or 10^^^ = 0.076 



a very low value in correspondence with the density of 

 solution. 



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, a6 is a manometer tube about 0.6 cm. internal 

 diameter, closed at both ends and containing about the 

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

 In this way the effect of temperature is diminished, 

 though it is necessary to obscr\^e 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. 



