CH. xxix. GALVANI AND VOLTA. 261 



without any metal at all. But Volta was not so easily con- 

 vinced ; he still insisted that it was the different fluids and 

 tissues being brought together which caused the electiicity, 

 and that there was not a current running through the 

 animal. At this point, just when the truth would probably 

 have been worked out, Galvani died (in 1798), leaving 

 Volta in possession of the field ; and for twenty-eight years 

 no more was heard of animal electricity. We know now 

 that both the professors were right. Volta was right in 

 saying that the convulsion of the frog's legs on the balcony 

 was produced by the contact of the two metals in con- 

 nection with a fluid ; while Galvani was right in saying that 

 there is an electricity in animals which acts without any 

 other help. In 1826 an Italian named Nobili repeated 

 Galvani's experiment, and having then an instrument called 

 a galvanometer (see p. 351), by which the passage of the 

 faintest electric current can be detected, he proved that 

 such a current does exist in the frog, and it has since been 

 found to be common to all animals. 



Meanwhile, however, Volta had also made a very re- 

 markable discovery, namely, that two different metals when 

 joined together in contact with moisture, and separated from 

 other substances, produce a current of electricity. This 

 may easily be tried in its very simplest form. If you take 

 a piece of copper and a piece of zinc and put one above 

 your tongue and one below it, you will feel nothing remark- 

 able so long as the two metals are kept separate, but directly 

 you let them touch each other at the ends, a tingling sensa- 

 tion will pass through your tongue, proving to you that an 

 electrical current is passing between the metals. If you put 

 the zinc under your upper lip, so that the copper may re- 

 main outside, you may, perhaps, even see a slight flash 

 when the two metals meet. 



