296 CONCERNING THE EFFECT OF GRAVITY 



(3) The substance must lend itself readily to the detec- 

 tion of change in concentration. 



It seems likely that some organic solutes and solvents can 

 be found which will have all these factors at a maximum. Data 

 on the first two factors can be found for some substances in 

 Landolt Bornstein's tables, and of these cane sugar seems to bo. 

 one of the most satisfactory. It has a large diffusion constant, 

 and can be obtained very pure, and its concentration can be 

 accurately estimated by the polariscope. 



The following calculations are made for a tube 3 meters in 

 length, and D for cane sugar is taken as .300 as about the mean 

 of the results of Grahm and Arrhenius. 



D = .300 where the cm. is the unit of length, the gram the 

 unit of mass, and the day the unit of time. 



Calculation of the fall for one year ; that is, for a at x = 0, 

 and t = 365. 



- 10 x .3 x 365 - 9 x 10 x 0.3 x 365 



Sa 

 it 



i \J *. **J * u\ju *s *> xv A. v.t- /> tut/ 



9000CTxT 90000~xT~ \ 



4- ) 



7T 



-0.012 -0.108 



( 



^ (0.988. + 0.098 .................... \ 



= o.9a approximately. 



So that in a tube of this length the fall in concentration of 

 the sugar solution at the end of one year would only be about 

 one-tenth of the total fall after an infinite time. For a con- 

 centration of 1 to 4 this would be about ten per cent, of 



-7 -6 



10x10 x 150 = 15x10 gr. which is a change of con- 

 centration that in a solution of that strength would defy detec- 

 tion, 



