Proceedings of the British Association. 351 



Art. XIII. — Abstract of the Proceedings of the Twelfth Meeting 

 of the British Association for the Advancement of Science. 

 Condensed from the Report in the London Athenceum. 



(Concluded from p. 172.) 



Sect. B. Chemistry and Mineralogy. 



Dr. Playfair read an abstract of Prof. Liebig's Report on Or- 

 ganic Chemistry applied to Physiology and Pathology. We 

 omit the summary of this communication, as Prof. L.'s highly 

 interesting and important work has been widely circulated in this 

 country. 



Mr. Mercer communicated a paper on some peculiar instances 

 of the (so called) Catalytic Action. Mr. M. had long considered 

 that instances of catalysis were merely examples of chemical 

 affinity, exercised under peculiar circumstances. A body never 

 entirely yields up its chemical characters on uniting with other 

 bodies. The iron in protoxide of iron, has still an affinity for 

 more oxygen, and has not lost that affinity by its first union with 

 that element. The intensity of affinity by which the simple 

 elements are joined in the complex molecule, must be the meas- 

 ure of the stability of the compound. Mr. M. argued, that when 

 the elements of a body are in mere static equilibrium by virtue 

 of a feeble attraction, and when it is acted upon by another body 

 possessing an affinity for one of its constituents, which constitu- 

 ent on the other hand, from peculiar circumstances, is not prone 

 to combine with it, that in such a case, so called catalysis must 

 ensue. Thus on mixing oxalic acid and nitric acid with a little 

 water, and raising the temperature to 130°, no action ensues. 

 But if a small portion of any protosalt of manganese be now 

 added, the decomposition immediately commences, and all the 

 nitric is converted into nitrous acid, whilst the oxalic acid passes 

 into carbonic acid. He thus accounts for this singular action : 

 The carbonic oxide of the oxalic acid has a disposition to unite 

 with oxygen ; to gratify this disposition, it endeavors to with- 

 draw it from nitric acid, but it is not sufficiently powerful to do 

 so ; stjll it places the atoms of the nitric acid in a state of ten- 

 sion. Another body (protoxide of manganese) now being intro- 

 duced, which also has an affinity for oxygen, exerts this affinity, 

 and the combined forces thus acting upon the nitric acid, occa- 



