) 352 GALVANISM. 



quart of this water was accordingly evaporated in a silver still at a terr. . : --.- ' 

 ture below 140, and a saline residuum teas obtained weighing seven tenth c \ 

 a grain. 



The gold cups were now again filled with the water thus purified, ai.d ?,; 

 posed to the Voltaic action. After two hours the cup N failed to show tri : 

 alkaline efi'ect on turmeric paper. By very minute observation, its effec 4 : c -\ { 

 tin- more delicate test of litmus was perceivable ; but this disappeared by the 

 application of heat, and was, therefore, ascribed to ammonia produced by the 

 combination of the small quantity of azote contained in the water with the 

 nascent hydrogen. 



Finally, in order to insulate the results from the disturbing effects of the sur- 

 rounding atmosphere, the gold cups containing the purified water were placed 

 under the receiver of an air-pump, which was exhausted until the gauge stood 

 at half an inch. Hydrogen gas was then introduced under the receiver, which, 

 mixed with the very minute portion of atmospheric air which had remained, 

 was again withdrawn by the pump. Pure hydrogen gas was now once more 

 introduced around the cups, which being placed in connexion with the Voltaic 

 apparatus, were suffered to remain under its action for twenty-four hours, at the 

 end of which time neither of the portions of the water altered in the slightest 

 degree the tint of litmus. 



Thus were dispelled the speculations on the power of electricity to generate 

 new principles in water ; and by eliminating the disturbing action of other 

 causes, the decomposing- power of the pile upon a binary compound was pre- 

 sented in a manner fitted for theoretical investigation. 



If chance occasionally deprives the philosopher of the merit of discovery by 

 throwing facts under his feet, an ample field for the exercise of his sagacity 

 remains in the due appreciation of the innumerable effects which are incidental 

 to his experimental researches ; to seize which as they arise, to pursue them 

 through their consequences, to strip them of the Protean disguises which they 

 borrow from other phenomena with which they become related, to expand them 

 by comparison and generalization into comprehensive natural laws, is the prov- 

 ince of the highest powers of philosophical inquiry. Never was this felicitous 

 instinct more conspicuous than in the mind of Davy. No effect, however mi- 

 nute or accidental it might apparently be, presenting itself in his experiments, 

 escaped his vigilance, if it offered the least clue to further discovery. In the 

 course of the experiments just noticed, he found himself embarrassed by the 

 disturbing action of the Voltaic wires on the material of the vessels containing 

 the liquid, which was the immediate object of his attention. One material 

 after another was put aside to get rid of this effect ; but ihe fact was not over- 

 looked or forgotten. It proved the germ of a vast discovery. 



The negative wire effected a partial decomposition of the glass and agate 

 cups, and brought a portion of their constituents into solution in the water con- 

 tained in them. Might not a power, which thus subdued affinities so stubborn 

 as those which produce the aggregation of substances so insoluble as agate and 

 glass, be brought to bear on other similar bodies, and perchance resolve into 

 their components substances now considered simple and elementary? As a 

 first trial of the decomposition of insoluble or difficultly-soluble bodies, cups 

 were formed of wax, resin, marble, argillaceous schist from Cornwall, serpen- 

 tine from the Lizard, and graywacke. Being filled with purified water* in the 

 same manner as in the experiments above described, decomposition was in all 

 cases effected and saline matter evolved. 



Pursuing this investigation, he successively decomposed by the same pro- 



* By purified water in all the following experiments is to be understood water rendered chemi- ) 

 cally pure by the processes above described. 



