80 Intelligence and Miscellaneous Articles. 



of the hailstone, without distinct indications of a different deport- 

 ment from the rest of the solid apparently homogeneous mass of the 

 granule. But as soon as the line of fusion reaches the spherical 

 bubble of the granule, the bubble rapidly recedes from the line of 

 fusion, expanding to more than fifty times its former volume. 



The diameter of the individual granule is from 0-0544 to 0*0724 mil- 

 lim., the diameter of the individual spherical body which is exactly 

 in the centre of the granule, and which is seen to be a minute air- 

 bubble, is 0*0088 millim. From what is observed on the melting of 

 the granule, the bubble is air, yet air which is condensed to one- 

 fiftieth of its original volume. The individual air-bubbles, which im- 

 mediately after their expansion have under the ordinary atmospheric 

 pressure a diameter of 0*02716 to 0*0314 millim., swim for a short 

 time without change in the ice-water of the object-table. As the 

 volumes of spheres are to each other as r 3 : r/ 5 , 



r 3 ^ (Q-0044) 3 



r/ (0-0157) 3 ' ' 



As according to Boyle's law V : V / =P / : P, in order to compress a 

 bubble of air of the density of ordinary air from 0*0271 millim. dia- 

 meter to a volume of 0*0088 diameter, a pressure of 52 atmospheres 

 must have been exerted. Assuming that the hailstones were formed 

 under the ordinary pressure, we may calculate the temperature at 

 which a mass of air under the ordinary pressure would be contracted 

 to 52 times as small a bulk. Since 



then 



Yt^Vt-Vtcct,, 



h ~~Yt^r 



the value for the two volumes, reduced by four decimal places, is 

 _ f _ 0*11304-0*00216 _ 



' 0*11304x0*00458 



From this unusual degree of cold it is probable that the sole cause 

 of condensation is not cold alone ; probably both causes have been 

 operative in this enormous condensation of the air in the solid mass 

 of ice. 



Continual observation and comparison of many hailstones showed 

 me that the condensed air-bubbles are in the middle of the spherical 

 granule of the hailstone, and that the enclosed air which is disen- 

 gaged from the melting hailstone is neither in the solid ice which 

 fills the interstitial space between the individual granules, nor in the 

 homogeneous solid mass of the granule. Refraining from any hints, 

 I wish to direct the attention of observers to this interesting fact, and 

 I recommend the subject to further observation. — Poggendorff's 

 Anmlen, No. 4, 1871. 



