334 



ANDREWS 



ART. I 



In addition to these experiments, which have involved true 

 equihbrium, mention should be made of the interesting deter- 

 minations of the effect of gravity on the electromotive force of 

 cells. 



Tolman^^ has shown that much valuable information on 

 the nature of solutions can be obtained by studying the electro- 

 motive force which is produced when a solution of uniform con- 

 centration is placed in a centrifugal force field. This e.m.f. is 

 due, of course, to the fact that the concentration is uniform, 

 and would disappear if diffusion were allowed to bring the 

 concentration to the equilibrium values, such as we have been 

 calculating from the above equations. 



The same principles have also been applied to particles in 



TABLE III 



The Molecular Weight of Hemoglobin as Determined by Sedi- 

 mentation Equilibrium 



electric and magnetic fields, notably in the work of Langevin'^ 

 on the nature of paramagnetism. 



REFERENCES 



1. Laplace, Mecanique Celeste, Book I, Chap. VIII, Paris 1799. 



2. Beudant, Ann. chim. phys., 8, 15 (1815). 



3. Gay-Lussac, Ann. chim. phys., 11, 306 (1819). 



4. GouY and Chaperon, Ann. chim. phys., [6] 12, 384 (1887). 



5. Einstein, Annal. Phys., [4] 17, 549 (1905). 



6. Perrin, Comples rendus, 146, 967 (1908); Ann. chim. phys., [8] 18, 



53 (1909). 



