GALVANISM. 



357 



examined, proved to be potash and lime, but no strontia had yet arrived in the 

 cup. In half an hour, however, strontia appeared, and in four hours was 

 / abundant. 



A piece of the muscular flesh of beef was used in like manner as a siphon 

 ' connecting the two cups, P containing a solution of muriate of baryta, and N 

 distilled water. Soda, ammonia, and lime, appeared first in the water, an.l 

 after about an hour and a quarter the baryta began to arrive. Muriatic acid \\ . 

 abundantly liberated in the cup P. 



It is nothing more than a general expression of the phenomena which have 

 been just detailed to say, that hydrogen, alkaline matter, metals, and certain 

 metallic oxides, are attracted toward the negative, and repelled from the posi- 

 tive pole of a Voltaic apparatus ; and that oxygen and acid substances are 

 affected with a similar attraction and repulsion in the contrary direction. 



As to the actual process by which the transfer of the element decomposed 

 takes place, either between the positive and negative wires in the solution un- 

 der decomposition, or through the intermediate solution, no distinct opinion was 

 expressed in the paper now noticed. Davy showed that it is natural to sup- 

 pose that the repellent and attractive energies are conveyed from one particle 

 to another of the same kind, and that locomotion (of these particles) takes place 

 in consequence. He considered this to be proved by many facts. Thus when 

 an acid was drawn from the negative to the positive cup through an alkaline 

 solution contained in the intermediate cup, if the Voltaic action was for a mo- 

 ment suspended before the transfer of all the acid in the negative cup had been 

 effected, traces of acid were always discoverable in the intermediate cup. It 

 appears from this that the series of acid molecules, while moving between the 

 ends of 'the amianthus siphons in the intermediate cup, do not enter into com- 

 bination with the alkali ; but if the motion be for a moment suspended, com- 

 bination instantly takes place. In this case, therefore, it would not appear that 

 any supposition of transmission by a series of decompositions and recomposi- 

 tions is compatible with the phenomena. 



In the cases, however, of the decomposition of water (where the whole men- 

 struum between the decomposing wires is water), and of solution of neutral 

 salts (where also the menstruum is altogether composed of the same solution), 

 he admits that there may possibly be a succession of decompositions and re- 

 compositions throughout the fluid. He admits, also, that the impossibility of 

 transmitting through an acid or alkali any element which forms with it an in- 

 soluble compound, although the transmission is perfect when the compound is 

 soluble, supports the hypothesis of a succession of compositions and decompo- 

 sitions taking place in every case. He maintains, that although in some cases 

 insoluble substances are transmitted, the transmission is effected in a manner 

 totally different from that which takes place in the more general case. The 

 insoluble matter was, in these cases, carried over mechanically, either through 

 the interstices of the siphons, or by means of " a thin stratum of pure water, 

 where the solution had been decomposed at the surface by carbonic acid." 



It appears from the tenor of the observations in this paper, " on the mode 

 of decomposition and transition," that the mind of the author had not yet ar- 

 rived at any opinion satisfactory to himself on this subject. 



By the experiments of Volta it had been shown that different metals brought 

 into contact were oppositely electrified after separation. Davy found that an 

 acid and a metal being in contact, the former became negative, and the latter 

 positive ; but that when an alkali and a metal were in contact, the electrical 

 | effects were reversed. As a general fact it appeared, therefore, that positive 

 electricity has a tendency to pass from acids to metals, and from metals to al- 

 kalies, and negative electricity to flow in the opposite direction. Diffeient 



