6 Professor T. E. Thorpe [Jan. 17, 



part of the antiphlogistic doctrine of Lavoisier, although the points 

 of view were diametrically opposed. Neumann attempted to obtain 

 a metal from lime, Bergman considered that baryta was, like lime, a 

 metallic calx, and Baron that alumina contained a metal. From their 

 many analogies to these substances it was not unreasonable, there- 

 fore, to surmise that potash and soda might also contain metallic 

 principles. 



I have elsewhere pointed out that there is some evidence that 

 whilst at Bristol Davy had akeady attacked the problem of the 

 resolution of the alkalis by means of voltaic electricity. What pre- 

 cise idea he had in again attacking it, or what expectation he had of 

 a definite result, is difficult to determine. In one of his lectures on 

 Electro-chemical Science, delivered some time subsequently, he said 

 he had a suspicion at the time that potash might turn out to be 

 " phosphorus or sulphur united to nitrogen," conceiving, that as tne 

 volatile alkali was composed of the light inflammable hydrogen 

 united to nitrogen, so the fixed and denser alkalis might be composed 

 of the denser inflammable bodies — phosphorus and sulphur — also 

 united to nitrogen. 



Davy once said that " analogy was the fruitful parent of error," 

 and few more striking instances of perverted analogy are to be met 

 with in science than this. In another of his lectures he said of the 

 alchemists that " even their failures developed some unsought-for 

 object partaking of the marvellous " ; and if such had been his 

 reasoning, the statement is no less true of himself. 



So far as can be ascertained, it was on October 10, 1807, that he 

 obtained his first decisive result. This is thus described in Davy's 

 own handwriting in the I^aboratory Journal, which has been pre- 

 erved for us by the pious care of Faraday, and which is one of the 

 most precious of the historical possessions of the Royal Institution : 

 "When potash was introduced into a tube having a platina wire 

 attached to it, so [fig.], and fused into the tube so as to be a con- 

 ductor — i.e. so as to contain just water enough, though solid — and 

 inserted over mercury, when the platina was made negative, no gas 

 was formed and the mercury became oxydated, and a small quantity 

 of the alkaligen was produced round the platina wire, as was evident 

 from its quick inflammation by the action of water. When the 

 mercury was made the negative, gas was developed in great quantities 

 from the positive wire, and none from the negative mercury, and 

 this gas proved to be pure oxygen — a capital experiment, proving the 

 decomposition of potash," 



On the 19th of the follo^\ing month he delivered what is generally 

 regarded as the most memorable of all his Bakerian Lectures. It is 

 entitled " On some New Phenomena of Chemical Changes produced 

 by Electricity, particularly the Decomposition of the fixed Alkalies ; 

 and the Exhibition of the new substances which constitute their 

 bases ; and on the general Nature of Alkaline Bodies." 



