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SCIENCE. 



[N. S. Vol. VIII. No. 19S. 



electrolytic docompositiou of water, just 

 alluded to, by Nicholson and Carlisle; the 

 deposition of the metals lead and silver 

 (probably the beginning of electro-chemical 

 analysis) ; tlie remarkably mysterious and 

 quiet passage of oxygen from the end of 

 the silver terminal over to the zinc terminal, 

 where it appeared as gas — all observed by 

 Cruikshank ; the discovery by Davy that 

 the current set free hj^drogen and oxygen 

 from water in the proportion in which they 

 united to form the parent substance ; the 

 conclusion reached byTlitter that reduction 

 invariably took place at one pole while 

 oxidation occurred at the other; the evolu- 

 tion of Grothuss' theory in regard to the 

 decomposition of liquids generally by the 

 current — a theory highly suggestive in vari- 

 ous directions. Thus, the esterification 

 theory of Willianison is based upon the 

 same idea of alternate decompositions and 

 re-formations ; the magnificent conquests 

 made by Davy, culminating in the isolation 

 of the interesting and valuable alkali metals, 

 sodium and potassium ; giving to the chem- 

 ical world not only two new elements, but 

 also inciting students the world over to re- 

 searcli in wide-reaching fields— a discovery 

 pronounced by Ostwald to be ' the close of 

 the first act of the electro-chemical drama,' 

 and yet what wonderful progress had been 

 made through the application of the new 

 agent. But richer discoveries were to fol- 

 low. Recall the labors of Berzelius and 

 Hisinger, upon which was founded a theory 

 now almost forgotten, and in its day a re- 

 tardcr, in some measure, of the proper 

 understanding of simple chemical combina- 

 tions. But it was helpful and contributed 

 sit least a mass of facts, applied later suc- 

 ■cessfuUy in the solution of various chemical 

 problems. And as we advance I must not 

 fail to mention Becquerel, de la Rive and 

 Ffaff", who contributed much of lasting 

 value during the controversy waged by the 

 adherents of opposing schools in regard to 



the origin of the current, in the midst of 

 whom appeared the immortal Faraday, fix- 

 ing the relation between the electrical 

 magnitudes and the combining numbers of 

 chemistry, really taking the initial steps 

 in the foundation of the quantitative period 

 of electro-chemistry. I must not, however, 

 dwell too long upon the many observations 

 made by him. Let suffice the mere men- 

 tion of his identification of machine and 

 Volta electricity; his declaration concern- 

 ing electro-chemical decomposition that ' the 

 effect is produced by an internal corpus- 

 cular action, exerted according to the direc- 

 tion of the electric current, and that it is 

 due to a force either superadded to or giving 

 direction to the ordinai-y chemical affinity 

 of the bodies present;' his suggestion, after 

 wrestling with the nomenclature of that day 

 prevalent in electro-chemistry, of the terms 

 anode, kathode, electrode, ion, etc.; his 

 efforts to measure electricity when he wrote 

 ' that the decomposing action of the current 

 is constant for a constant quantity of elec- 

 tricity,' and following this thought con- 

 structed an instrument Avhich, ' being inter- 

 posed in the course of the current used in 

 any particular experiment, should serve at 

 pleasure either as a comparative standard of 

 effect or as a positive measurer of this sub- 

 tile agent.' Again, having repeated all his 

 earlier experiments with the most varj'iug 

 conditions, he wrote ' variations in the in- 

 tensity * * * produced no difference as to 

 the equal action of large and small elec- 

 ti'odes;' and when he had completed his 

 volta-electrometers they were so arranged 

 that " after the current had passed through 

 one it should divide into two parts ; these 

 after traversing each one of the remaining 

 instruments should reunite. The sum of 

 decomposition in the latter two vessels was 

 always equal to the decomposition in the 

 former vessel * * -1= exactly the same 

 quantity of Mater was decomposed in all 

 the solutions by the same quantity of elec- 



