Observations on the Study of Mineralogy. 43 



loaded with such materials as these, and floating either in or on 

 the atmosphere : they would be differenlly electrified ; for oxvgen 

 with its contained materials, and hydrogen with its accompani- 

 ments, would certainly be so. 



The effect of two such masses coming into collision, would be 

 exhibition of liglit and communication of heat. — The two elec- 

 tricities rushing into contact would produce explosion ; the gases 

 would be ignited*; the stony materials undergo fusion, — and 

 in that moment the formed aerolite would take its flight to the 

 earth. 



As to the change in the proportional constituents, the powers 

 of electricity will account for this. Has not Sir H. Davy proved 

 that the usual powers of nature may be controlled by its action ? 

 By giving foreign electric properties to alkalies and acids, has he 

 not changed their relations, and destroyed their natural attrac- 

 tions ? 



The metals concerned in this extraordinary fabric are suscep- 

 tible of receiving magnetic phcenomena. Electricity permanently 

 identified with iron or nickel may impart to them this property, 

 vested in only a privileged few. A fine steel bar electrified be- 

 comes maijnetic, and the action of lightning has reversed the 

 polarity of the mariner's compass. 



Dr. Clarke has found that meteoric stones become magnetic 

 after fusion by the oxyhydrogen blow-pipe, which may proceed 

 from a volatilization of" tlie sulplmr ; for it is known that the pre- 

 sence of either arsenic or sulphur weakciis or destroys this suscep- 

 tibility. I have the honour to be, sir, 



Your very humble and most obedient servant, 



J. Murray. 



VII. Observations on the Study of Mineralogy. By Robert 

 Bakewell, Esq.-f 



JVliNERALorTY is a branch of natural history; and he who would 

 obtain a just and comprehensive view of the subject, must not 

 confine his attention to minerals as they are arranged in cabinets, 

 but contemplate them as they occur in their native repositories; 

 he shouhl endeavour to tr.'ice the connexion between diflTcrcnt 

 species of minerals, and the changes whicli they undergo by |)ro- 

 cesses of natural chemistry — changes which cannot at present 

 l)e imitated in our laboratories. Persons who live principally in 



• The oxidation of the thin shell of the aeiolite h in hiirnidiiy with this 

 view. Aqiu'ous viipour would be (ornied by the i;;nitioii of the j^ascs, and 

 impart that ap])earance which it has received IVoiii some such means. 



t Kxtraefed t'lom the Preface to Mr. liakewell's Introduction to Minera- 

 logy just published. 



large 



