JNTKODUCTION. 



great purposes of nature ; we behold the one employed in 

 the individual combination of substances, the other in the 

 general arrangement of the whole. We behold the contradic- 

 tory opinions of theory, and the diversity of appearances in 

 nature, connected and harmonizing with the truths of mo- 

 dern chemist ry !" * 



Nor must it be forgotten that our ideas of a chaotic state 

 seem to be confined to this globe only, instead of being at 

 least extended to our solar system. And if we conceive, with 

 La Place, that the planetary bodies were formed by the con- 

 cretion of an aeriform fluid, emanating from the sun, which 

 derives its splendour from the Deity, the fountain of light, 

 human imagination can never conceive the universal effer- 

 vescence and developement of various vapours and gases, 

 which must have appeared in the primeval universe. But in 

 this and other grand ideas the prince of modern philosophers 

 will ever be found to lead the way, having thus expressed 

 Newton's himself in his immortal PRINCIPIA. " The vapours which 

 arise from the sun, the fixed stars, and the tails of comets, 

 may fall by their gravity into the atmospheres of the planets, 

 where they may be condensed and converted into water and 

 humid gases j and afterwards by a slow heat graduate into 

 salts, and sulphurs, and tinctures, and mire, and mud, and 

 clay, and sand, and stones, and corals, and other earthy sub- 

 stances.'^ Did not this eagle of intuition thus foresee the 

 pneumatic chemistry ? 



The important geological observations of Dr. Davy on the 

 subject of volcanoes also excite, and may authorise, some 

 other general remarks on the theory of the earth, which will 

 not, it is hoped, be found wholly digressive. 



* Sketch of a New Demonstration of Nature, London 1810, 8vo. 



f Vapores autem qui ex sole, et stellis fixis, et caudis cometarum oriuntur, 

 incidere p)ssunt per gravitatem suam, in atmosphaeras planetarum ; et ibi con- 

 densari, et convert! in aquam et spiritus humidos : et subinde, per calorem len- 

 tum, in sales, et sulphura, et tincturas, et limum, et lutum, et argillam, et 

 arenam, et lapides, et coralla, et substantias alias terrestres, paullatim migrare. 



NEWTON Princ.part ii. prop. 42. 



