250 - 



potash or soda was to increase the time necessary for this transfer. 

 Muriatic or nitric acids were also transmitted through alkaline solu- 

 tions ; and, vice versd, alkaline matter, by changing the arrangement 

 of the liquids, was transmissible through the acids : even magnesia 

 was transferred like the other bases. But when it was attempted to 

 pass sulphuric acid through aqueous solutions of barytes or of stron- 

 tian, on the contrary, the sulphate of those earths was deposited in 

 the intermediate tube. 



Muriate of barytes being positive, sulphate of potash intermediate, 

 and water negative, potash appeared in the water, and sulphate of 

 barytes was deposited in the intermediate vessel. 



Muriate of barytes being negative, sulphate of silver intermediate, 

 and water positive, sulphuric acid only appeared in the water, and 

 muriate of silver was deposited in the intermediate vessel. 



Mr. Davy then proceeds to develop the theory of these pheno- 

 mena : and he first considers the mode of decomposition and transi- 

 tion. Hydrogen, alkaline substances, and metallic oxides, are at- 

 tracted by negatively electrified metallic substances, and repelled by 

 positive ones : contrary effects take place with oxygen and the acids. 

 He thinks these electric energies are communicated from one particle 

 to another of the same kind, so as to establish a conducting chain in 

 the fluid, as acid matter is always found in the alkaline solutions 

 through which it is transferred, as long as any acid matter remains 

 at the original source. It is possible that there may be, in some 

 cases, a succession of decompositions and recompositions ; but the 

 process is not absolutely necessary, as pure acids and alkalies pass 

 through water to the points by which they are attracted. It appears 

 that this power of transference is overcome by gravity in attempting 

 to pass barytes through sulphuric acid, or muriatic acid through sul- 

 phate of silver. To these instances he adds, that magnesia and the 

 metallic oxides will not pass through an intermediate vessel of water, 

 but sink to the bottom. 



In the decomposition of water, a particle of oxygen is attracted by 

 the positive point, and at the same time a particle of hydrogen is re- 

 pelled by it; the opposite process takes place at the negative point: 

 and in the middle of the circuit there must be a new combination of 

 the repelled matter, in the same manner as when two portions of 

 muriate of soda are separated by water ; muriatic is repelled from 

 the negative side, and soda from the positive side ; so that muriate 

 of soda is composed in the middle vessel. 



Although similar effects could not be produced by silently passing 

 a strong current of electricity from an electrical machine for four 

 hours, through sulphate of potash, yet they were produced by using 

 platina wires -yVth of an inch in diameter, cemented in glass tubes ; 

 so that no doubt can arise but that the principle of action is the same 

 in common as in voltaic electricity. 



It was known that many bodies brought into contact and then se- 

 parated, exhibited opposite states of electricity ; and Mr. Davy him- 

 gelf had observed, that when acid and alkaline solutions were em- 



