of Researches in Electricity. 463 



Iceland spar ; these being cut so as to have the axis of the crystal 

 parallel to the line joining two opposite faces of the cube ; but 

 the experiments, which are laborious, require extension, and he has 

 not as yet been able to prove or disprove the expected result. 



The author then considers whether in compound bodies it is the 

 ultimate and elementary particles or the compound particles which 

 polarize as wholes. He concludes that it is the latter which assume 

 that state ; and shows how this point bears upon the electrolyzation 

 of such bodies as are separated into simpler substances, or otherwise 

 altered by the action of the voltaic current. 



He then proceeds to certain experiments bearing upon the nature 

 of the relation of the electric and magnetic forces, giving his view 

 of the character of this relation ; and concludes his paper by briefly 

 stating what he thinks is more satisfactorily explained by the theory 

 which refers inductive action to an action of contiguous particles 

 than by the old theory. 



•'Experiments on the Vibration of the Pendulum." By W. J. 

 Frodsham. Communicated by Francis Beaufort, Capt. R.N., F.R.S. 



The object of this paper is to show the advantages that may re- 

 sult from attaching to the top of the pendulum a brass tube, which 

 the author terras " an isochronal piece," about five inches in length, 

 fitting the pendulum very nicely, and slit so as to form a spring for 

 about an inch at the bottom, sliding rather stiffly on the rod, so that 

 its position, and consequently its influence on the action of the 

 pendulum, maybe varied at pleasure; and that unequal arcs of vibra- 

 tion may be made to correspond to equal intervals of time. 



"An Account of some Experiments on the Blood in connexion 

 with the Theory of Respiration." By John Davy, M.D., F.R.S., 

 Assistant Inspector of Army Hospitals. 



The author has investigated, experimentally, several of the im- 

 portant questions connected with the theory of respiration and of 

 animal heat ; and arrives at the following results. He finds that 

 the blood is capable of absorbing oxygen both from atmospheric air, 

 and from oxygen gas, independently of putrefaction. After blood 

 has been agitated in common air, a trace of carbonic acid, not ex- 

 ceeding one per cent., is found in the residual air; but when pure 

 oxygen is employed, no carbonic acid can be detected in it by the most 

 carefully conducted trials. When pure carbonic acid is brought 

 into contact with blood, or serum, over mercury, and moderately 

 agitated, the absorption of gas exceeds the volume of the fluid. 

 Both arterial and venous blood are rendered very dark, and serum 

 more liquid by the absorption of this gas to saturation. Serum, in 

 its healthy state, is incapable of absorbing oxygen, or of immediate- 

 ly furnishing carbon to form carbonic acid : and after it has ab- 

 sorbed carbonic acid, only one-tenth of the absorbed gas is expelled 

 by successive agitation with atmospheric air, or with hydrogen. The 

 author is inclined to think that the alkali in the blood, in its 

 healthiest condition, is in the state of a sesquicarbonate. In the 

 majority of trials manifest indications of the disengagement of air 

 from blood in vacuo were obtained : but as it occasionally happened 



