THE CONCENTRATION OF A SOLUTE. — DAVIS. 



ISTor would any material advantage be obtained by either 

 shortening or lengthening the tube, for in the first case the 

 total effect is decreased and soon gets beyond the limit of detec- 

 tion, and in the other, the time to obtain the same percentage 

 fall is increased so as to so-on debar experimental verification. 



This effect would then l)e difficult to show in the laboratory, 

 i^xccpt perhaps for some organic substances, and for these there 

 is no available data on ditt'usion constants or on density. In 

 nature, however, there are immense bodies of water in the 

 ocaen. These have been there for a long time, though with 

 disturbing factors, and here this efi'ect might be detected. 



Practically the only comprehensive and reliable data on the 

 composition of sea water is to be found in the Reports of H. 

 M. S. Challenger, Physics and Chemistry, vol. 1. A great 

 number of samples of waters from various latitudes and depths 

 were secured and analysed. The whole results are given. There 

 is also an excellent report on deep-sea temperatures. 



Xow it will be well to consider whether there are other 

 factors present which would modify the efi'ect in question. 

 These are : 



(1) Ocean currents which tend by continually stirring up 



the water to keep the whole at constant concentration. 



(2) The efi'ect of hydmstatic pressure. In the article 

 referred to above, Vegard assumes thnt the iluid is 



incompressible and his results are worked out on that 

 assumption. (See also Ostwald. Solutions. Muir's 

 translation, 1804, p. 61). 



(3) Temperature. 



The effect of temperature on the concentration of a solute 

 is difficult to ralculato for this reason. 



Vhoc. & Trans. \. .«. TNsr\ Sci., Voi,. XII. TkAVs '.>:i. 



