5JI6 Notices respecting Nevi Books. 



lily be oxide of iron, which would thus be presented, in a state of 

 minute division, to incandescent, but enormously compressed free hy- 

 drogen, by which, agreeably to known results of experiment, it would 

 be reduced to the metallic form, water being re- composed. A 

 new affinity would now come into action : finely divided metallic 

 iron being in intimate contact with the earthy and alkaline oxides, 

 they would be reduced, as in the ordinary method of obtaining potas- 

 sium and the process by which Davy and Berzelius first succeeded in 

 de-oxidizing the combustible bases of silica and alumina, and would 

 eventually re-act upon the water still present. By this constant cir- 

 culation of affinities, exerted simultaneously in diflferent portions 

 of the heated mass, according to their respective temperatures and 

 to the local distribution within it of the various substances evolved, 

 (dependent on their respective properties, as modified by the enor- 

 mous pressures to which they would be subject,) chemical equili- 

 brium would alternately be established and subverted ; and all the 

 phsenomena and effects of plutonic and volcanic action would ensue 

 — as originally suggested by Davy; — but as simple consequences of 

 the secular variation of the isothermal surfaces, as explained by Bab- 

 bage and Herschel ; the latter theory being a wider generalization, 

 and including the former as one of its elements. 



Mr. Poulett Scrope's views of the origin and constitution of lava, 

 &c. hitherto regarded as so anomalous, were also briefly alluded to 

 as other probable truths involved in the new theory ; and the com- 

 munication terminated with some general reflections, including the 

 remark, that the names of Babbage and Herschel united would now 

 descend to posterity associated with the history of geological dyna- 

 mics, as they had already been with the improvement of many branch- 

 es of mathematical analysis, and with the progress of some of the 

 more recondite departments of physical science. 



May 18. — Mr. Faraday on the solid, liquid, and gaseous state of 

 carbonic acid, illustrated by Thilorier's apparatus. 



LXXX. Notices respecting New Booh, 



Description d'une Collection de Min^raux, formee par M. Henri Heu- 

 land, et appartenant a M. C. H, Turner, de Rooksnest, dans le ComU 

 de Surrey en Angleterre. Par A. L4vy, Membre de VUniversite de 

 France, etc. Trots volumes, avec un Atlas de 83 Planches, 



WE have quite accidentally omitted sooner to notice the above very 

 valuable work on Mineralogy, for such we deem it to be, al- 

 though described merely as a catalogue. Those who are engaged in 

 the examination of minerals, and particularly of their crystalline forms, 

 cannot fail to derive much useful assistance and instruction from 

 this publication. It appears from a notice prefixed to the work, we 

 presume by M. Heuland, that many years had been occupied in 

 forming the collection, and under peculiarly favourable opportunities, 

 for obtaining the finest and most rare specimens of every variety of 

 mineral. The prefatory notice also states that the descriptions 

 were drawn up several years since by M. L^vy, and might, if he had 



