Barus — Nuclei produced by Shaking Different Liquids. 81 



Art. YII. — On the Numbers of Nuclei produced by Shak- 

 ing Different Liquids and Allied Results y by C. Barus. 



1. In my report on the nucleus," I showed that the number 

 produced in a given mode of comminution was least in pure 

 water, greater in dilute organic solutions and still greater in 

 dilute inorganic solutions, all of the same strength. Results 

 were also given for other solvents than water, in particular for 

 benzol ; but I was unable to reduce the data to the same scale 

 as for aqueous solvents, as the data needed for the reductions 

 were not at hand. I have since found that the method of 

 Wilson and Thomsonf lends itself to benzol and have, there- 

 fore, computed the data over again as shown in Table I. 



The pressure reduction used to effect the condensations was 

 throughout Bp = 16 cm . Hence at about 20° the adiabatic fall 

 of temperature in case of a benzol-air medium should be as 

 far as —10*2°, the rise of temperature thereafter (due to con- 

 densed liquid) to 11'3°, and consequently the liquid benzol 

 precipitated per cubic centimeter m = 30-4 XlO" 6 grams. The 

 goniometer factor was a = '0031 = d s, being the product of 

 the diameter d of the fog particle and the apertures of the 

 corona. Hence the number of nuclei per cubic centimeter is 

 finally n — 1*95 (10 s)% all the coronas in question being normal, 

 excessively intense and brilliant. 



This may be compared with water. The corresponding 

 temperature reduction of the water air medium is to —7*6°, the 

 rise of temperature due to the ensuing condensation as far as 

 9*5°, so that ??z = 4*5 X 10~ 6 grams per cub. cm., almost 7 

 times smaller than the corresponding datum for benzol. When 

 the same goniometer as above is used, therefore, n = '29 (10 s)*. 



Table I. — Number of nuclei produced by identically shaking solutions of 



one per cent concentrations. 



Nuclei per 

 Solution, etc. cm 3 of air. Solutes. 

 Pure water 130 



r\ • u j' ■ • a. ~o^ sucrose, glucose, glycerin, 



Organic bodies in water 630 ■<■ * * • -i 



° ( urea, tartaric acid 



f]Sra 2 S0 4 CaCl 2 Ca2NO, 

 Inorganic salts in water 1260 <j ^ ^ J^^' 



Naphthalene in benzol. 3500 

 Paraffine in benzol 5000 



LNa,P0 4 HClH 4 NNO f 



* Smithsonian Contrib., No. 1373, chap, v, 1893. 

 fPhil. Mag. (5), xlvi, p. 538, 1898. 



Am. Jour. Scl— Fourth Series, Vol. XVII, No. 97.— January, 1904. 

 6 



