252 POPULAR SCIENCE MONTHLY. 



were powerfully agitated. We can only speak of this discovery as 

 the stumbling on to an isolated fact, for it was reserved for Volta 

 to establish the generalization that a current is produced in the con- 

 ductor joining dissimilar metals when the latter are both in contact 

 W'ith a suitable electrolyte (or liquid capable both of conducting elec- 

 tricity and of acting on one, and incidentally also sometimes both, 

 of the metals). Meantime (Du Bois-Reymond observes), " wher- 

 ever frogs were to be found, and where two different kinds of metal 

 could be procured, everybody was anxious to see the mangled limbs 

 of frogs brought to life in this wonderful way. Physiologists be- 

 lieved that at last they should realize their visions of a vital power, 

 and physicians that no cure was impossible." 



Yolta first discovered merely the fact of electrification by con- 

 tact. He wrote to Galvani: " I don't need your frog. Give me two 

 metals and a moist rag, and I will produce your animal electricity. 

 Your frog is nothing but a moist conductor, and in this respect it is 

 inferior to my wet rag! " iN^obili, nevertheless, in 1825 proved the 

 existence of galvanic currents in muscles. 



Later on Yolta invented the " couronne des tasses " (crown 

 of cups), thus at the same time adopting the general form of cell 

 used, with modifications, to-day, and producing the higher electro- 

 motive force, or electrical pressure, consequent on the multiplication 

 of the cells in a series battery. 



Just before Yolta's celebrated communication to the Royal Soci- 

 ety, in 1800, Fabroni, of Florence, in discussing Galvani's phenome- 

 non, went to the root of the matter by suggesting that the energy of 

 chemical action was at the bottom of galvanic manifestations, and he 

 was warmly upheld in this contention by Sir Humphry Davy, who, 

 upon the publication of Yolta's discoveries, constructed a most 

 elaborate battery with which (apparently about 1806) he produced 

 the arc light between carbon j)encils. 



In the year referred to, Davy published the results of a series 

 of experiments of enormous significance, among other things of 

 the isolation of the alkali metals, sodium and potassium, whose 

 existence had hitherto not been dreamed of. The simple electro- 

 lytic decomposition of water had been accomplished by Xicolson 

 and Carlisle in the last year of the eighteenth century. Sir "VV. S. 

 Harris says : " A scries of new substances was speedily discovered, 

 the existence of which had never before been imagined. Oxygen, 

 chlorine, and acids were all dragged, as it were, to the positive pole, 

 while metals, inflammable bodies, alkalies, and earths became deter- 

 mined to the negative pole of the battery. When wires connected 

 with each extremity of the new battery were tipped with prepared 

 and well-pointed charcoal, and the points brought near each other, 



