Dr. Faraday's Researches in Electricity. 455 



animal frame, is capable of being applied in producing a useful 

 mechanical effect, — the remaining three-quarters being re- 

 quired in order to keep up the animal heat, &c. 



Prof. Magnus of Berlin, has endeavoured to prove that the 

 oxygen which an animal inspires does not combine chemically 

 with the blood, but is merely absorbed by it*. The blood thus 

 charged with oxygen arrives in the capillary vessels, where 

 the oxygen effects a chemical combination with certain sub- 

 stances, converting them into carbonic acid and water. The 

 carbonic acid, instead of oxygen, is then absorbed by the 

 blood, and thus reaches the lungs to be removed by contact 

 with the atmosphere. Adopting this view, it becomes exceed- 

 ingly probable that the whole of the vis viva due to the oxida- 

 tion or combustion of the "certain substances" mentioned by 

 Magnus is developed by the muscles. The muscles, by their 

 motion, can communicate vis viva to external objects; and, 

 by their friction within the body, can develope heat in various 

 quantities according to circumstances, so as to maintain the 

 animal at an uniform temperature. If these theoretic views 

 be correct, they would lead to the interesting conclusion (which 

 is the same as that announced by Matteucci from other con- 

 siderations) that the animal frame, though destined to fulfill so 

 many other ends, is, as an engine, more perfect in the ceco- 

 nomy of vis viva than the best of human contrivances. 



LXXVI. Experimental Researches in Electricity. — Twentieth 

 Series. By Michael Faraday, Esq., D.C.L., F.R.S., 

 Fullerian Prof., fyc. fyc. 



[Concluded from p. 406.] 

 % iv. Action of magnets on metals generally. 

 22S1. HPHE metals, as a class, stand amongst bodies having 

 A a high and distinct interest in relation both to 

 magnetic and electric forces, and might at first well be expected 

 to present some peculiar phenomena, in relation to the striking 

 property found to be possessed in common by so large a number 

 of substances, so varied in their general characters. As yet 

 no distinction associated with conduction or non-conduction, 

 transparent or opake, solid or liquid, crystalline or amorphous, 

 whole or broken, has presented itself; whether the metals, 

 distinct as they ai'e as a class, would fall into the great gene- 

 ralization, or whether at last a separation would occur, was to 

 me a point of the highest interest. 



2288. That the metals, iron, nickel and cobalt, would stand 

 in a distinct class, appeared almost undoubted ; and it will be, 

 * [See Phil. Mag. S. 3. vol. xxvii. p. 56] .] 



