﻿On Coloured Cloudy Condensation, 19 



Values of 

 (1/Mx + 1/M S )*/ {(M^) V2 + (M a &) »/2} f D(l + A/273) = 1/B273^ 



H 2 and 



H 2 . 



0,. 



N, 



CO. 



CH t . 



00 2 . 







•144 



•144 



•153 



•133 



•135 



Air and 



'•144 



•140 









•123 



C0 2 and 



•135 



•122 



'•123 









H 2 and 



N 2 0. 



C 2 H 4 . 



C 3 H 6 2 . 



C 4 H 8 2 . 



O 5 H 10 O 2 . 



C 6 H 12 2 . 





•138 



•131 



•150 



•157 



•163 



•166 



Air and 







•119 



•123 



•127 



133 



C0 2 and 



•125 





•113 



•110 



•114 



•115 



H 2 and 



C 7 H u 0. v 



C 8 H 16 2 . 



C 9 H 18 2 . 



(C 2 H 5 ) 2 0. 



CS 2 . 



C 6 H 6 . 





•167 



•177 



•178 



•157 



•150 



•150 



Air and 



•132 



•139 



•142 



•123 



•125 



•115 



C0 2 and 



•115 



•119 



•123 



•107 



•107 



•100 



Winkelmann's values of the diffusion-coefficients for the 

 vapours of water, the alcohols, and fatty acids have not been 

 discussed in the present communication on account of the 

 exceptional nature of these substances, but they will doubtless 

 be of value when the time is ripe for a full discussion of the 

 physical reasons of their exceptional behaviour. 



Melbourne, January 1894. 



II. Coloured Cloudy Condensation, as Depending on the 

 Temperature and the Dust-contents of the Air. By Carl 

 Barus * 



[Plate V.] 



1. TN the "koniscope" Mr. Aitken | has expressed the 

 J- dust-contents of a given sample of air, in terms of 

 the colour, or of the intensity of colour, or of the amount of 

 exhaustion necessary to produce a given colour, when the 

 cloudy condensation is produced by sudden expansion of the 

 gas in a suitable tube, containing enough moisture to satu- 

 rate the air. The importance of temperature is pointed 

 out, but not evaluated. Mr. Aitken prefers to make the 



* I have availed myself of the permission of the Editors of this Maga- 

 zine to reproduce here a condensed account of certain parts of a forth- 

 coming Bulletin of the U.S. Weather Bureau, "believing the subject to 

 possess some general physical interest. 



f Aitken, Proc. Roy. Soc. London, li. p. 425 et seq., 1892. For a 

 review of the earlier history of the subject (for which there is no space 

 here) the reader is referred to my papers in the ' American Meteorological 

 Journal,' ix. p. 488, 1893; x. p. 12, 1893. On reviewing my resume I 

 find that the tribute there paid to the breadth and thoroughness of Mr. 

 Aitken's researches (many of which I have since repeated) is inadequate. 

 I therefore feel bound to make this acknowledgment. 



C2 



