158 



IJIK STKUCrUliE OF THE NUCLEUS. 



Fur iieutial litiiiul ori^'aiiio solutes in aqueous solution of 1 to 3 % h — 'o; for 

 solutions of .01 % n — 12. Nuclei from these bodies are thus very fleeting. 



Finally for liydrocarbon .solution of solid hydrocarbons of 1 to 3 %, «=r.lO 

 or .20, not ditt"erin<; much in persistence, etc., from the salt solutions. 



The total range found for the diffu.sion velocity of nuclei produced by sliaking 

 solutions of less than 3 ^ is thus from « = .1 to w = 50 cm/min., increasing with 

 the degree of dilution of the solution, the largest value cited (j)ure water) closely 

 ;tliproaching the datum for phosphorus nuclei in atmospheric air, « = 00 cni/miii. 



These vailations of the velocity of the nuclei produced by shaking, and its 

 r.'latiou to the order of values I'esulting from the direct experiments with phos- 

 l>horus nuclei given in table 12, is accounted fur by the thermodynamic hypothesis 

 for their occurrence, which makes of them particles of concentrated solution. The 

 size of the nucleus for a given solvent depends essentially on the extremely small 

 mass of solute which it happens to contain. It is larger when shaken from the 

 more concentrated dilute solutions than from the weaker solutions, because the 

 critical density is reached in the former case with less evaporation, and the capillary 

 increment of vapor pressure to be com[)ensated is at the same time smaller. 



Thus, it is quite reasonable to suppose that the nuclei obtained from phos- 

 phorus or other emanations will be smaller, and, therefore, more mobile than the 



T.ABLK .3.— COMP.\RISON OF DIFFUSION VELOCITIES. 



(i) Nil' It-I |irt]duced by shaking. 



I'urc Benzine 



72 



.070 



•36 



(2) Nuclei introduced from without. 



Direct measurements for 1 

 phosjjhorus nuclei in J- 

 benzol vapor 



Do. in toluol vai)or 



' Color yellowish. Naphthalene emits nuclei spontaneously. 



