52 Royal Society. 



circumstances, it was found that the volume of the gas was un- 

 altered, and that a similar quantity of oxygen gas had been abs- 

 tracted, but that a much smaller quantity of carbonic acid had 

 been formed than in the last experiment, the remaining portion 

 being made up by azotic gas which had been given out from the 

 lungs of the bird, and the volume of which was just equal to that 

 of the oxygen absorbed. The bird vvas somewhat disturbed during 

 the experiment, but recovered immediately and perfectly on being 

 released from its confinement. 



In the fourth experiment, in which a pigeon was made to respire 

 a mixture of oxygen and hydrogen with a small proportion of azote 

 (the oxygen being in the same proportion as in common air), it 

 was found that there was no loss of oxygen ; but that a quantity of 

 hydrogen disappeai'ed, and was replaced by an equal volume of 

 azote. The authors observe, that birds have a quicker circulation 

 of blood than other animals ; and also, that they are more sen- 

 sible to the stimulating effects of oxygen. 



May 7. — A paper was read, entitled " Experimental Examina- 

 tion of the Electric and Chemical Theories of Galvanism ;" by 

 William Ritchie, A.M. F.R.S. 



After showing that the theory of galvanism originally proposed 

 by Volta, and generally termed the electric theory, is still the uni- 

 versall}'^ received doctrine among continental philosophers, the au- 

 thor adduces several experiments proving the fallacy of the princi- 

 ples on which that theory is founded. He points out the inconclu- 

 eiveness of the reasoning by which it has been inferred, that dissi- 

 milar metals, by being simply placed in contact with one another, 

 ire instantly thrown into opposite electric states : for in all the ex- 

 periments which have been made with a view of establishing this 

 fundamental principle of the electric theory, the metals have been 

 exposed to the oxidizing action of the air, which is a constant 

 source of electric disturbance, and the operation of which has been 

 strangely overlooked. The author found, by forming galvanic 

 circles with two different metals and an interposed acid, that when 

 he used different kinds of acid, or varied the degree of their dilu- 

 tion, the electro-magnetic effects, as measured by a delicate galva- 

 nometer, bear no sort of relation to the conducting power of the 

 fluid, as is assumed in the voltaic hypothesis. He deduces the same 

 conclusion from experiments made with an apparatus by which the 

 fluid is confined in a rectangular box, divided by a membranous 

 diaphragm into two compartments, so as to allow of the addition 

 of an acid to the fluid contained in one of the compartments, 

 and thereby limiting its action to one of the metallic surfaces. By 

 means of another contrivance, the author ascertained, that of two 

 different metals, the one which when acted upon by an acid com- 

 bines with the greatest quantity of oxygen, as measured by the vo- 

 lume of hydrogen disengaged, is always positive with respect to 

 the other metal. Even two pieces of the same metal, differing 

 in hardness, will be acted upon by the same acid in different 

 degrees, and may thus be brought into different states of elec- 

 tricity. In general it is the harder of the two pieces of metal 



which 



