GALVANIC ELECTRICITY. 51 



vidnals \vlm have been fortunate enough to lay open to the world a 

 new law of nature. 



It lias been doubted by many persons, whether the voltaic and 

 electrical energy were the same : but thousands of experiments 

 might be offered to prove them to be such. M. de Luc's very sim- 

 ple aerial electroscope, or electrical column, as he calls it, may be 

 adverted to, as sufficient of itself to establish this fact. This co- 

 lumn consists of zinc. plates and Dutch gilt. paper, in regular sue. 

 cession, like the metallic plates of the voltaic pile, the groups being 

 from one thousand to ten thousand. When two of these columns 

 are placed horizontally, the one insulated, and the other communi- 

 cating with the ground, each being terminated with a small bell, and 

 a small brass ball is suspended between the two bells by a silken 

 thread, the ball, by the mere influence of the electricity contained 

 in the atmosphere, will chime, by striking alternately from column 

 to column, and consequently from bell to bell, sometimes more 

 or less rapidly, and sometimes more or less loudly, and sometimes 

 scarcely at all, according to the state and proportion of the electric 

 aura ; and the instrument, which is a genuine voltaic pile, not only 

 proves the identity of the electric and voltaic power, but may be 

 conveniently employed as a measurer of the electricity which the at- 

 mosphere contains. It should he observed, however, that as there 

 are no fluids known, except such as contain water, that are capable 

 of being made the medium of connexion between the metals, or 

 metal of the voltaic apparatus, the effect in this, and in all similar 

 instances, is resolved by Sir Humphry Davy into some small quan- 

 tity of moisture, or water still existing in the substances employed, 

 which he asserts will not act if each of the substances be made per- 

 fectly dry. 



The first distinct experiment upon the igniting powers of large 

 voltaic plates was performed by MM. Fourcroy, Vauqueliu, and 

 Thenard ; but a much grander combination for exhibiting the ef- 

 fects of extensive surface was constructed by Mr. Children, and con- 

 sists of a battery of twenty double plates four feet by two; of which 

 the whole surfaces are exposed, in a wooden trough, in cells co- 

 vered with cement, to the action of diluted acids. 



The most powerful combination, however, that exists, in which 

 numbers of alternations is combined with the extent of surface, is 

 that constructed by subscriptions of a few zealous cultivators and 

 patrons of science, in the laboratory of the Royal Institution. It 

 consists of two hundred instruments, connected together in regular 



