282 ACTION OF SURFACE. 



to that of catalytic power, that the secretion of such 

 different bodies is produced, all which are supplied by 

 the same matter, the sap in plants, and the blood in 

 animals."* 



It is, without doubt, to this peculiar agency that we 

 must attribute the abnormal actions produced in the 

 blood of living animals by the addition of any gaseous 

 miasma or putrid matter, of which we have, in all pro- 

 bability, a fearful example in the progress of Asatic 

 cholera ; therefore the study of its phenomena becomes 

 an important part of public hygiene. 



Physical research has proved to us that all bodies 

 have peculiar powers, by which they condense with 

 varying degrees of force gases and vapours upon their 

 surfaces ; every body in nature may, indeed, be regarded 

 as forming its own peculiar atmosphere. To this power, 

 in all probability, does catalysis belong. Different 

 views have, however, prevailed on this subject, and Dr. 

 Lyon Playfairf argues that the catalytic force is merely 

 a modified form of chemical affinity, exerted under 

 peculiar conditions. 



Whatever may be the power producing chemical 

 change, it acts in conformity with some fixed laws, and 



* Berzelius : Annales de Chimie, vol. Ixi. 



f On Transformations produced by Catalytic Bodies : by Lyon 

 Playfair, Esq.; Phil. Mag., vol. xxxi. p. 191, 1847. "Facts have 

 been brought forward to show that there is at least as much pro- 

 bability in the view that the catalytic force is merely a modified 

 form of chemical affinity exerted under peculiar conditions, as 

 there is in ascribing it to an unknown power, or to the commu- 

 nication of an intestine motion to the atoms of a complex mole- 

 cule. Numerous cases have been cited, in which the action 

 results when the assisting or catalytic body is not in a state of 

 change; and attempts have been made to prove, by new experi- 

 ments, that the catalytic power exercises its peculiar power by 

 acting in the same direction as the body decomposing, or entering 

 into union, but under conditions in which its own affinity cannot 

 always be gratified." 



