Royal Society. 59 



After removing from the water the deliquescent chlorides of lime 

 and magnesia by the addition of carbonate of" soda, he transmits 

 through the mother liquor, consisting of chloride and bromide of 

 sodium, a current of chlorine gas, till it communicates the maximum 

 golden tint, and then adds sulphuric aether, which, by agitation, car- 

 ries with it to the surface the bromine and chlorine, constituting a 

 reddish yellow stratum. The proportion in which these two elements 

 exist in the evaporated solution may be ascertained with the greatest 

 nicety by the addition of a solution of nitrate of silver ; the method of 

 calculation for this purpose being detailed by the author. 



7. *' On the Nature and Origin of the Aurora Borealis." By the 

 Rev. George Fisher, M.A., F.R.S. 



The author deduces from his own observations made during a re- 

 sidence of two winters in high northern latitudes, taken in con- 

 junction with the concurring testimony of various navigators and tra- 

 vellers, the general fact that the Aurora Borealis is developed chiefly 

 at the edge of the Frozen Sea, or wherever there is a vast accumu- 

 lation of ice 5 and he conceives that it is produced in situations where 

 the vapours of a humid atmosphere are undergoing rapid congelation. 

 Under these circumstances, when viewed from a distance, it is seen 

 fringing the upper border of the dark clouds, termed the ** sea blink," 

 which collect over these places ; and it generally forms an arch a 

 few degrees above the horizon, shooting out vertical columns of pale 

 yellow light. He concludes that the Aurora Borealis is an electrical 

 phenomenon, arising from the positive electricity of the atmosphere, 

 developed by the rapid condensation of the vapour in the act of 

 freezing, and the induced negative electricity of the surrounding 

 portions of the atmosphere j and that it is the immediate consequence 

 of the restoration of the electrical equilibrium by the intervention of 

 the frozen particles, which being imperfect conductors, become lumi- 

 nous while transmitting this electricity. In tropical and temperate 

 climates this phenomenon does not occur, because the electric equi- 

 librium is restored by means of aqueous vapours, a process which 

 often gives rise to thunder and lightning, but never to the Aurora 

 Borealis ; the latter being peculiar to clear, cold and dry weather. 



8. " Th^orie Balistique." Far M. Le Comte de Pr^daval. Com- 

 municated by Dr. Roget, Sec. R.S. 



The author inquires into the influence which he conceives the fol- 

 lowing circumstances may have on the path of a projectile on the 

 surface of the earth ; namely, first, the direction of the line of pro- 

 jection relatively to the meridian or cardinal points ; secondly, the 

 latitude of the place ; and thirdly, the barometric conditions of the 

 atmosphere. 



9. *' On the Atmospheric Tides and Meteorology of Dukhun, in the 

 East Indies." By Lieut.-Colonel W. H. Sykes, F.R.S. 



The author premises detailed descriptions of the various instru- 

 ments used in the meteorological observations recorded in this paper, 

 and of the methods employed in obtaining his results ; of which the 

 great features are the barometrical indications of diurnal and noc- 



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