Valency of the Radio-elements. 597 



the action of secondary forces into colloidal hydroxides, &c. 

 From the variety of such secondary forces one would expect 

 a corresponding variety of results from diffusion experiments 

 in those kinds of solutions. Thus the diffusion constant, 

 measured in neutral solution, of thorium B which is similar 

 to lead shows the electrolytic nature of the former, while 

 polonium is still, to a large extent, colloidal in 1/1000 N 

 hydrochloric acid solution. 



Diffusion of thorium B from dilute KC1 solution into water. 



Dl5°-6. Disc 



L rwe °' 73 °' 78 



IL rrHra °' 76 °- 81 



iv. ~ °' 73 c ' 78 



Mean value for D 18 o is 0*79 sq. cm. per day, which corre- 

 sponds to 80 per cent, completely dissociated lead chloride. 



Diffusion of thorium B from distilled water 

 into 2N alcohol. 



D150.2. Diso. 



!• 1& °- 48 0>52 



"• rrae °- 56 °- 60 



IV - ITO7 °' 47 °' 51 



The value found for Di 8 o must be multiplied by 1*13 * to 

 eliminate the retarding influence of the added alcohol, and 

 the value for Di 8 o thus becomes 0*61 sq. cm. per day. This 

 is the diffusion constant of completely dissociated (ThB)Cl 2 . 



Diffusion of radium F from 1/000 N hydrochloric acid 

 solution into a hydrochloric acid solution of the same 

 concentration which is also 1 X with respect to alcohol. 



D150.2. Diso. 



L 1TOT0 °"M °^ S 



tt °' 57 o-23 0-94 



1J - 1-76x1-43 U - t3 V ^ 



III. °' 57 — 022 0-23 



1-79x1-45 " U ~° 



IV. 17Q ' 5 ? K 0-22 0-23 



l-/9xl-45 

 * Arrhenius, Zeit.phys. Chem. x. p. 51 (1892). 



