BiograpJikal Memoir of' Sir Humphry Davy. 15 



the analogies of the fixed alkalies with alkaline earths, and of 

 the latter with metallic oxides, and Lavoisier had even announced 

 the possibility of these earths being oxides, incapable of being 

 reduced by the ordinary means. With respect to the fixed al- 

 kalies properly so called, whatever conjectures had been formed 

 as 'to their composition, results from some combinations with 

 azote ; the analogy with ammoniac had led to this idea ; but in 

 science the most happy conjectures are unavailing, if not con- 

 firmed by experience. 



Mr Davy being in possession of such a powerful means of de- 

 composition as the pile, did not despair of resolving the import- 

 ant problem. After having tried it without success on some 

 aqueous solutions, he took potash sufficiently moistened to make 

 it serve as a conductor, and having placed it in the circle of a 

 powerful battery, the positive side produced a violent efferves- 

 cence, while at the negative side there appeared small globules, 

 resembling quicksilver in colour and lustre, but so combustible 

 that they were covered almost while they formed, with a white 

 crust of potash, and which, when thrown upon water, remained 

 on the surface, and burned with a bright flame and considerable 

 heat ; it was the same upon ice, and it looked as if he had re- 

 covered the wild fire so famous in Byzantine history, to which it 

 is probably owing that Europe is not at the present day under 

 the influence of Mahometanism. The same phenomena pre- 

 sented themselves with soda, and whatever were the conductors, 

 the produce of the combustion was always potash or soda; an 

 envelope of naphtha was the only means of preventing these 

 metallic globules from attracting oxygen, so as to counteract 

 their tendency to combustion. It was in vain that some con- 

 tended that these new substances were combinations of hydro- 

 gen, or even carbon, with the alkalies ; rigorous analysis speedily 

 exposed the error of such an hypothesis, and it remained demon- 

 strated that potash and soda resulted from the combination of 

 oxygen with bases resembling metals in their external charac- 

 ters, but infinitely lighter, and having an infinitely stronger at- 

 traction for oxygen. Potash contains 84 centiemes, and soda 

 76 centiemes, of metal. These bases, which are as perfect con- 

 ductors of heat and electricity as the other metals, become soft 

 at 12° of Reaumur, and at 30° become liquid like mercury, and 



