CONVERSATION XLIII. Of Galvanism; its Origin; Experiments.-Of the decom, position of Water. TUTOR. It has been observed as long as I can remember, and probably before I was born, that porter, when taken from a pewter pot, had a superior flavour than when drunk out of a glass, or china. Charles. Yes; I have often heard my uncle say so; but what is the reason of it? Tutor. Admitting the fact, which is, I believe, generally allowed by those who are much accustomed to that beverage; it is now explained upon the principles of Galvanism. James. Is Galvanism another branch of science? is there a Galvanic fluid as well as an electric fluid? Tutor. Of the existence of the electric fluid you now have no doubt; the science of electricity took its name from electron, the Greek word for amber, because amber was one of the first substances observed to produce, by rubbing, the effects of attraction and repulsion. Galvanism derives its name from Dr. Galvani, VOL. III.-X who first reported to the philosophical world the experiments on which the science is founded. Charles. Pray how was he led to make the experiments? Tutor. Galvani, a professor of anatomy at Bologna, was one evening making some electrical experiments, and on the table where the machine stood, were some frogs skinned: by an accident one of the company touched the main nerve of a frog, at the same moment that he took a considerable spark from the conductor of the electrical machine, and the muscles of the frog were thrown into strong convulsions. These, which were observed by Galvani's wife, led the professor to a number of experiments, but as they cannot be repeated without much cruelty to living animals, I shall not enter into a detail of them. James. Were not the frogs dead which first led to the discovery? Tutor. Yes, they were: but the professor afterwards made many experiments upon living ones, whence he found that the convulsions, or as they are usually called, the contractions produced on the frog, may be excited without the aid of any apparent electricity, merely by making a communication between the nerves and the muscles with substances that are conductors of electricity. Charles. Which are the best conducting substances? |