148 REVISIONS OF THE THEOEY OF ELECTEOLYSIS. 



water consisted of a union of these two gases only. They cited 

 both the synthesis and the analysis taking place in their experimental 

 tube as proofs of their view. But the question as to the manner in 

 which electricity acts to effect the decomposition remained unan- 

 swered. They did not obtain the two gases separately, but mixed 

 in the glass tube. An enormous number of discharges were said 

 to be necessary to produce an appreciable volume of mixed gases — 

 14,600 for one-third of a cubic inch. 



A little later Ritter found that 50 or 60 discharges from a Leyden 

 jar through a solution of silver nitrate between silver wires gave 

 a visible deposit of metallic silver on the negative electrode. By 

 reversing the poles this deposit disappeared, and at the same time 

 a new deposit formed on the other wire. 



It is therefore obvious that the scientific world was prepared to 

 accept electrolytic decomposition when Volta disclosed his invention 

 of the dry pile and the voltaic battery, or " crown of cups." This 

 disclosure was made in a letter to Sir Joseph Banks, president of 

 the Ro3^al Society of London, dated March 20, 1800. Before this 

 letter was published in the Philosophical Transactions its contents 

 had become known to London physicists, and Nicholson and Carlisle 

 had decomposed water by means of Volta's pile. Carlisle made the 

 acute observation that when a drop of water was placed on the upper 

 plate of the pile to improve the contact between it and the wire of 

 the external circuit, gas was given off; and Nicholson recognized 

 the presence of hydrogen when the wire used was steel. These and 

 similar facts induced them to send the electric current from a pile 

 of 36 pairs through river water between brass wires in a glass tube 

 half an inch in diameter. A fine stream of gas bubbles was at once 

 given off from the negative electrode. One- fifteenth of a cubic 

 inch was obtained in an hour and a half, and when this was mixed 

 with an equal volume of air the mixture exploded on the approach 

 of a lighted wax taper. 



Although these observers expected the decomposition of water, 

 they were not prepared for the astonishing fact that, while the 

 hydrogen appeared at the exposed end of one of the wires, the 

 oxygen appeared only at the end of the other, nearly 2 inches 

 distant. This phenomenon was to its discoverers inexplicable. They 

 made the very relevant and acute remark that this new phenomenon 

 " appears to show perhaps a general law of the action of electricity 

 in chemical processes." The explanation of this remarkable fact 

 has ever since engaged the attention and best endeavors of science. 



It is worthy of attention also that Nicholson and Carlisle observed 

 that chemical action takes place in a voltaic cell Avhen it functions as 

 a source of current. In other words, they recognized that a voltaic 

 cell is also an electrolytic cell. This is the first of many facts which 



