ELECTRO-CHEMISTRY. 9 



which the iodide of potassium was decomposed ? 

 There can be no escape, I should think, from the con- 

 clusion that the positive electricity was derived from 

 the acid, and the negative electricity from the 

 alkali. 



7. The materials with which I operate are neces- 

 sarily so very small in quantity, particularly when I 

 introduce liquids into glass tubes, that the results, 

 though positive, may be thought trivial. Thus when I 

 introduce nitric acid into a glass tube, I first fill it with 

 acid, which is afterwards decanted, and the tube is 

 kept inverted until all the acid has dropped from it, 

 leaving only as much acid as adheres to the platinum 

 wire and the internal surface of the tube. The 

 quantity of acid which remains is not more than two 

 grains, or one grain and a half; if more than this, 

 the rupture of the tube, when exposed to an intense 

 heat, generally take place. It indeed requires a nice 

 adjustment in respect to the quantity of the materials 

 with which I operate, as well as the requisite hard- 

 ness and thickness of the tubes which I employ, in 

 order to resist, without fusion and without fracture, 

 the degree of heat to which, in the course of my 

 experiments, they are subjected. 



8. In October, 1857, I obtained what I had 

 hitherto failed to procure those German glass tubes 



