508 



nemisphere, the phenomena are found to present the same obvious 

 and decided features of a duplicate system as those of the northern. 

 Particular attention is given to those lines traversed by the ship's 

 course where the needle attains its maximum declination, whether 

 easterly or westerly, as affording valuable data for the estimation of 

 secular variations. The results obtained by the present expedition 

 confirm the conclusion deducible from those of previous navigators; 

 namely, that the spaces in the Southern Pacific, distinguished by 

 certain magnetic characters, undergo a movement of translation, of 

 which the general direction is from east to west ; a direction which 

 is the opposite to that in which a similar change takes place in the 

 corresponding regions of the northern hemisphere ; namely, in the 

 Siberian quarter, where the secular movement is from west to east. 



April 25, 1844. 



The MARQUIS OF NORTHAMPTON, President, in the Chair. 



1. "On the production of Ozone by Chemical Means." By C. 

 F. Shoenbein, Professor of Chemistry at Basle, in a second letter to 

 Michael Faraday, Esq., D.C.L., F.R.S. Communicated by Dr. 

 Faraday. 



The author adduces further evidence in support of the opinions 

 he advanced in his former communication relative to the identity 

 of the odoriferous principles which are disengaged during electric 

 discharges in common air, during the electrolysis of water, and 

 during the slow action of phosphorus upon atmospheric air. This 

 principle, termed Ozorie, he regards as being a simple body, and a 

 constituent of azote, which he believes to be a compound of hydro- 

 gen and ozone ; and he explains the disengagement of this latter 

 element, which he considers as analogous in its chemical character 

 to chlorine, by the partial decomposition of azote, in consequence 

 of its hydrogen combining with oxygen, in the several processes 

 above-mentioned during which ozone makes its appearance. 



2. " On the existence of Phosphoric Acid in Rocks of igneous 

 origin." By George Fownes, Esq., Ph. D., Chemical Lecturer in ' 

 the Middlesex Hospital Medical School. Communicated by Thomas 

 Graham, Esq., F.R.S. 



The author has, by careful analysis, ascertained the presence of 

 phosphoric acid in various rocks of igneous origin. Those which 

 he examined were principally the following; namely, 1. The fine 

 white porcelain clay of Dartmoor, resulting from the disintegration 

 of the felspar of the granite of that district. 2. Dark grey vesi- 

 cular lava from the Rhine, used at Cologne as a building-stone. 

 3. White trachyte from the Drachenfels, near Bonn. 4. Dark 

 red, spongy, scoriaceous lava from Vesuvius. 5. Compact, dark 

 green basalt, or toadstone from Cavedale, Derbyshire. 6. Dark 

 blackish-green basalt from the neighbourhood of Dudley, termed 



