48 



A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



thereafter (due to condensed liquid) to 11.3°, and consequently the liquid 

 benzol precipitated per cubic centimeter m = 30.4X10"" grams. The gonio- 

 meter factor was a = .0031 =ds, being the product of the diameter d of the fog 

 particle and the aperture s of the corona. Hence the ntimber of nuclei per 

 cubic centimeter is finally ^=1.95 {jos)\ all the coronas in question being 

 normal, excessively intense and brilliant. 



This may be compared with water. The corresponding temperatiue reduc- 

 tion of the water-air meditim is to —7.6°, the rise of temperature due to the 

 ensuing condensation as far as 9.5°, so that m = 4.5Xio'"'" grams per cubic 

 centimeter almost 7 times smaller than the corresponding datum for benzol. 

 When the same goniometer as above is used, therefore, n = .2g (los)-'. 



The curious result thus appears that the number of nuclei produced by a 

 definite amount of shaking is least for water, about 5 times greater for dilute 

 organic solutions in water, about 10 times greater for dilute inorganic solutions 

 in water, and about 30 to 40 times greater for dilute solutions of non-conductors 

 like naphthalene and parafifine in benzol. It is difficult to even conjecture a 

 reason for this behavior. 



3. Coronas in general. — The coronas in benzol for the above pressure 

 differences, dp, are all normal, even if nucleation from sulphur, phosphoiais, etc., 

 is introduced. From the slow diffusion of the vapor they soon become distorted 

 during successive exhaustions unless the vessel is shaken between them. It is 

 interesting to show, however, that in spite of the normal coronas the high 

 initial nucleation is fully accounted for. To do this I shall select a series of 

 observations for coronas in benzol vapor at random (/. c., p. 56). Sulphur 

 nuclei were used and the vessel shaken between observations. The table gives 

 the results. 



TABLE 2.— CORONAS IN BENZOL VAPOR. SULPHUR NUCLEL 

 n = 6m/7td'. m = 33Xio-°g. Per cub. cm. (i = . 00144/5. 



Sp= 18 cm. 



Comptited exponentially the initial nticleation would nm up into the 

 millions. The observations are not, however, in keeping with such a locus, and 



