Energy in Diffusive Convection. 525 



with an aqueous solution of concentration T, and that its upper 

 extremity is in contact with pure water. 



Fig. 2. 



Let v = velocity of liquid up the tube. 

 A= sectional area of the tube. 



With certain assumptions, it is shown in the paper on 

 " Diffusive Convection" that the difference of pressure between 

 the bottom and the top of the tube equals 



gL + 



gTh kgT 



■e * 



The external work done on the cylinder per second equals 

 the product of the volume which crosses any section and the 

 difference of pressure ; i. e., it equals 



v A (gL + 



<?TL kgT\ 

 r v J 



1-e 



= vA gL+ ^^ + k 9 TA. 



The work performed per second consists of two parts — 



(1) A quantity of water of volume vA is raised a height L. 



(2) A quantity of dissolved substance (see "Diffusive Oon- 



vAT 

 vection," Section II.) of amount ^ is raised a height L. 



