1819.] Analyses of Booh . 47 



Article VIII. 



Analyses of Books. 



Recherches sur PIdeutitt des Forces Chi/niques et Electriques. 

 Par M. H. C. (Ersted, Professeur a I' Cniversite Royale de 

 Copenhague, et Membre de la Societe Royale des Sciences de la 

 mane Ville, fyc. Traduit de PAllemand par M. Marcel de 

 Serres, Ex-Inspecteur des Arts et Manufactures, et Professeur 

 de la Facultt des Sciences a PUniversite Imperiale ; de la 

 Societe Philomatique de Paris, <Sc Paris, 1813. 



(Concluded from vol. xiii. p. 4C3.) 



Chap. VI. — Of the Production of Light. 



Our author considers it as established that both light and 

 heat are produced by the same kind of forces ; but in a different 

 state of activity. The evidences are, that it is a general law 

 that every body, when heated to a certain temperature, becomes 

 luminous ; and that, on the other hand, when light falls on a 

 body without being reflected, the body becomes hot. To eluci- 

 date this view of the subject, he goes over the different pheno- 

 mena of light, and shows that they all agree with his theory, and 

 serve to confirm it. With respect to the colours emitted by a 

 burning body, he is of opinion that when the force of combusti- 

 bility preponderates, the light emitted is blue or violet ; when the 

 burning force preponderates, the colour is red or yellow ; and 

 when they are in equilibrio, the light is green if the combustion 

 be feeble, and white if it be strong. 



I raav remark that some of the consequences naturally flowing 

 from this theory are hardly reconcileable with the present state of 

 our knowledge. Heat and light ought not to pass through a 

 perfect vacuum ; yet we know that electricity at least appears in 

 the torricellian vacuum. This last fact seems scarcely consistent 

 with the notion that the electric spark is merely incandescent 

 air. 



Chap. VII. — Observations on the Existence of the General Force* 



in Organic Bodies. 



The phenomena of animals (for those of plants have not been 

 examined under this point of view) exhibit abundance of proofs 

 of the existence of the general chemical forces in them. The 

 nerves are excellent conductors of electricity in the living animal, 

 and in conjunction with the muscles are capable of forming a 

 kind of galvanic circuit. Prof. CErsted conceives that the galva- 

 nic pile may serve to give us a kind of imperfect idea of the way 

 in which organic bodies act. He t.unks that muscular motion 

 may be accounted for by the galvanic energy exerted by the 

 nerves on the muscles. 



