24 



this purpose he contrived an apparatus which he designates by the 

 name of the dissected battery^ and which consists of a series of cylin- 

 drical glass vessels capable of holding the fluid electrolyte, with a 

 pair of metallic plates immersed in it, each plate communicating 

 below by means of a separate wire, with a small quantity of mercury, 

 as the medium of the various communications which may at pleasure 

 be made with other metallic parts of the apparatus. This arrange- 

 ment affords peculiar advantages for studying the difference of effect 

 in reference to the quantity and the intensity of the electric current, 

 consequent on the different modes of connecting the elements of the 

 battery, and also the influence of retarding forces resulting from 

 other modes of connexion. In the course of these researches 

 Mr. Daniell, observing the great extent of negative metallic surface 

 over which the deoxidating influence of the positive metal appeared 

 to manifest itself, was induced to institute a more careful examina- 

 tion of the circumstances attending this class of phenomena, and was 

 led to the discovery of the gradual deposition of zinc on the platina 

 plates being the principal cause of the progressive decline of the 

 power of the battery. It was then that the means of counteracting 

 this tendency presented itself to his mind. His plan consists in the 

 constant application of a solution of sulphate of copper to the copper 

 surface, while, at the same time, diluted sulphuric acid is constantly 

 applied to the zinc surface, on which it exerts an oxidating and a 

 solvent power, and is constantly renovated as it becomes charged 

 with zinc. The two fluids are separated from one another by a par- 

 tition formed of membrane, or other porous substance, which pre- 

 vents intermixture, but offers no obstacle to the transmission of 

 galvanic action. Two principal objects are accomplished by this 

 arrangement of the constituent parts of the battery ; first, the re- 

 moval out of the circuit of the oxide of zinc, the deposit of which 

 gradually reduces, and at length suspends, the action of the ordinary 

 battery ; and secondly, the absorption of the hydrogen evolved upon 

 the surface of the copper, without the precipitation of any substance 

 tending to counteract the voltaic action of that surface. 



The advantages likely to arise to science from the invention of 

 the constant voltaic battery are numerous and important. Mr. Da- 

 niell has shown how it may be made to supply a measure of chemical 

 affinity, and has applied it with effect in the investigation of the in- 

 fluence of changes of temperature on voltaic action. The construc- 

 tion of a constant battery of large dimensions, which he has recently 

 completed, has already opened new views of the possible application 

 to economical purposes of the powers of voltaic electricity, an agent 

 of which the influence appears to be so energetic and so widely dif- 

 fused throughout nature. 



The Council have adjudged one of the Royal Medals, in con- 

 formity with the announcement made in 1834, to Mr. Whewell, for 

 his series of Researches on the subject of the Tides, which have been 

 published in our Transactions during the last three years. 



Mr. Whewell's researches have been chiefly directed to the three 

 following points : first, the motion of the tide-wave at different points 



