C Barus — Flower-like Distortion of Coronas, etc. 309 



Art. XXY. — The Flower-like Distortion of the Coronas due 

 to Graded Cloudy Condensation ; by C. Barus. 



1. Recently I described* a series of results obtained most 

 satisfactorily with benzolf vapor, in which the coronas met 

 with are not closed and annular, but of a variety of patterns 

 from oval, with the long axis vertical to the symmetrically 

 open doubly inflected types (lyre-shaped or basin-shaped), run- 

 ning continuously into horizontal strata as the limiting case. 

 These distortions are due to the non-uniform distribution of 

 nuclei as to size, the largest having sunk deepest and the finer 

 nuclei floating uppermost, in virtue of the precipitation mech- 

 anism. When supersaturation is produced by adiabatically 

 cooling the benzol vapor, the condensation begins at the lower 

 strata and then passes upward as exhaustion proceeds and 

 higher degrees of supersaturation are reached. The evolu- 

 tion of coronas is peculiar in this case, and reminds one of a 

 person throwing out his arms laterally and upward until his 

 hands strike above his head. The sweep of coronal streamers 

 is outward and upward symmetrically with respect to the 

 vertical plane through the source of light. If the gradation is 

 not too rapid, they eventually coalesce above it. 



The droplets produced are finer above than below ; but it 

 does not follow that there are more particles in the upper 

 layers. The reverse will naturally be assumed. The lower 

 particles being larger have first received the condensation as 

 already suggested, and have thus grown biggest, as the oppor- 

 tunities for growth came earliest and lasted longest. 



2. It is my purpose in this paper to work out the shape of 

 the loci of like color when the nucleation is not uniform as to 

 size or number. The distributions arise from the subsidence 

 of loaded nuclei ; they are, therefore, horizontally stratified. 



In figure 1, let o be the distant point source of light into 

 which the coronas would shrink annularly and symmetrically 

 from without inward, to a limit in a normal case. Let be 



* Science, xv, pp. 175-178, 1902. 



f The nuclei do not originate in the benzol itself as I first supposed, but 

 are due (as I have since found) to the diffusion of a horizontal couche of 

 nuclei, brooding immediately over the surface of the liquid. For this 

 reason this residual layer is liable to escape detection on purifying the air of 

 nuclei by exhaustion. For my purposes it is a matter of little consequence 

 whence these residual nuclei come, and I have, therefore, not given much 

 attention to it. The occurrence of the diffusion is the essential feature. In 

 carbon disulphide, however, the nuclei certainly arise out of the liquid, 

 though it is not improbable that even here they are a foreign sulphurous 

 product. Saturation is soon reached at an enormously low but permanent 

 vapor tension. The question will soon be discussed elsewhere. 



Am. Jour. Sci. — Fourth Series, Yol. XIII, No. 76. — April, 1902. 

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