150 Dr Robert E. Brown on the 



other motions produced by external nature, may, either of themselves, 

 or by means of electricity thereby excited, effect some slight chemical 

 changes. The extent of these can hardly, however, be very great 

 and we shall not regard them at present. But a slight observation 

 of nature shews, that chemical and other molecular changes of gi-eat 

 extent take place among the component materials of the earth's sur- 

 face, and give rise to new forms, varieties, and affections of material 

 substances. Into the origin of these, therefore, it is now for us to 

 inquire. 



The earth being in the condition we have supposed, — ^being formed 

 and placed in relation to other matter as a planet, &c., and having 

 a variety of motions developed upon it, by the agency of the forces 

 belonging to that external matter, let it now be conceived that the 

 germs of vegetation, or of life nearly allied to it, are implanted upon 

 it. Under the influence of the terrestrial agencies of air and mois- 

 ture, applied to these germs by means of the heavenly bodies, in the 

 manner above shewn, and by the agency of the sun, directly through 

 its light and heat, the latent vital forces become active, and living 

 beings are produced. With the development of these new agents, 

 by far the greatest number of the chemical and other molecular 

 motions occurring upon the earth seem to be connected. For vital 

 force in action appears to run counter to, and to overcome, both gra- 

 vity and cohesion, but, above all others, the chemical forces. Thus, 

 for example, by its means carbonic acid and water, two of the most 

 stable chemical compounds which we know, and the hardest, and, to 

 all appearance, the most unassailable stony materials, have their che- 

 mical forces neutralised or overcome, the union of their component 

 elements broken up, and these elements arranged in a succession of 

 new combinations, at variance with, and in opposition to, the tenden- 

 cies of their whole chemical and mechanical natures. Now, the ex- 

 istence of each individual plant or being is temporary. On the com- 

 pletion of a seiies of operations, and the production of a definite re- 

 sult, it ceases to live ; the matter affected by its action comes again 

 under the dominion of the chemical and mechanical forces, and by 

 their means is brought back to its pristine condition, that it may be- 

 come the object upon which the vital forces of other beings may 

 operate. In this way there arise a vast number of chemical changes 

 and transformations. We shall afterwards endeavour to shew that 

 almost all chemical actions which occur upon the globe, either natu- 

 rally or such as are produced by art, are the results, direct or indirect, 

 of this descent of matter from an organic to an inorganic condition. 

 Tlie temporary existence of living beings individually, would almost 

 seem to be necessary to the pei-petuation of life. For in plants, at 

 least, life never seems to act without giving rise to growth, and 

 to the production of the germs of new individuals ; and, therefore, 

 with a definite and limited supply of matter, such as the earth af- 

 fords, vegetation, as it exists in this globe, could not be sustained 



