SIR HUAIPHREY DAVY. 6i 



To ascertain the qualities of the metallic residue which he had 

 thus obtained from the potash, was Davy's next object. From 

 its great attraction for oxygen, it almost immediately, when 

 exposed to the atmosphere, became an alkali again, by uniting 

 with that ingredient ; and at first it seemed on this account 

 hardly possible to obtain a sufficient quantity of it for ex- 

 amination. But at last Davy thought of pouring over it a 

 thin coating of the mineral fluid called naphtha, which both 

 preserved it from communication with the air, and, being 

 transparent, allowed it to be examined. 



We have thus rapidly sketched the course of these brilliant 

 and successful experiments, because they form a most interesting 

 and instructive exemplification of the manner in which know- 

 ledge is pursued, and the secrets of nature extorted from her 

 by well-directed interrogation. The business of philosophic 

 experiment, it may be well to observe, is not a mere random 

 expenditure of tests and applications. The true disciple of the 

 inductive philosophy, on the contrary, has always in his 

 contemplation, while conducting his experiments, an idea or 

 end which he aims at realising, and which, in fact, directs him 

 to every experiment to which he resorts. Thus, in the present 

 instance, the idea in Davy's mind was, that the alkali was 

 compounded of two ingredients which had severally an attraction 

 for the two opposite poles of the electric current. This idea he 

 never lost sight of throughout the whole course of his experi- 

 ments, though he repeatedly shifted his ground in regard to the 

 contrivances by which he sought its proof and manifestation. 

 To proceed in any other way would not be to philosophise, but 

 merely, as it were, to dip the hand into the bag of chance in 

 quest of a discovery, as men draw prizes at a lottery. It is 

 true that, until the experiment has cc.nfirmed or refuted liis 



