Читать книгу An Account of the Late Improvements in Galvanism - Giovanni Aldini - Страница 11

The heterogeneity of metals contributes, in a great degree, to excite muscular contractions with more facility, but is not absolutely necessary to their production.

This proposition I could demonstrate in a direct manner, by means of experiments, which I published formerly, on the contractions excited by very pure mercury, and which were repeated, in different ways, by the celebrated Humboldt. I am, however, happy to have an opportunity of examining the influence of arming with heterogeneous substances; and I shall endeavour to prove that it cannot, of itself, produce the effect of muscular contractions.

EXPERIMENT I.

If several prepared frogs, ten or more for example, be placed on a table (Plate I. fig. 7.), and arranged parallel to each other, in such a manner that the whole system of the nerves shall be at one end, and that of the muscles at the other—on applying two armatures and a metallic arc to the first of these frogs, muscular convulsions will be immediately excited, not only in the first frog, but in all the rest.

EXPERIMENT II.

If the experiment be repeated with the frogs arranged in such a manner that the spinal marrow and muscles are not each at one end (Plate I. fig. 8.), but disposed alternately so that the spinal marrow of one touches sometimes the muscles of another, or vice versa, convulsions will then be produced only in some of the frogs, and not in the whole series. This experiment proves that the effect does not, in any manner, depend on the action of metals; because metallic electricity in the first experiment ought to exercise an action only on the first frog, and not on the rest; and, in the second, ought to cause them all to move together, or to leave them motionless.

I shall now proceed to those experiments which appear to be best calculated to support the opinion of the great analogy between electricity and Galvanism.