S38 Dr. Faraday's Experimental Researches in Electricity. 



ject to any action from the oxygen evolved against it. The 

 arrangement is given fig. 16. 



798. In an experiment of this kind the equivalent for the 

 lead came out 93*17, which is very much too small. This, I 

 believe, was because of the small interval between the positive 

 and negative electrodes in the oxide of lead, so that it was not 

 unlikely that some of the froth and bubbles formed by the oxy- 

 gen at the anode should occasionally even touch the lead re- 

 duced at the cathode, and re-oxidize it. When I endeavoured 

 to correct this by having more litharge, the greater heat re- 

 quired to keep it all fluid caused a quicker action on the cru- 

 cible, which was soon eaten through, and the experiment 

 stopped. 



799. In one experiment of this kind I used borate of lead 

 (408. 673.). It evolves lead, under the influence of the elec- 

 tric current, at the anode, and oxygen at the cathode; and as 

 the boracic acid is not either directly (4-08.) or incidentally de- 

 composed during the operation, I expected a result dependent 

 on the oxide of lead. The borate is not so violent a flux as 

 the oxide, but it requires a higher temperature to make it 

 quite liquid; and if not very hot, the bubbles of oxygen cling 

 to the positive electrode, and retard the transfer of electricity. 

 The number for lead came out 101*29, which is so near 

 to 103*5 as to show that the action of the current had been 

 definite. 



800. Oxide of Bismuth, — I found this substance required 

 too high a temperature, and acted too powerfully as a flux, to 

 allow of any experiment being made on it, without the appli- 

 cation of more time and care than I could give at present. 



801. The ordinary protoxide of antimony, which consists 

 of one proportional of metal and one and a half of oxygen, 

 was subjected to the action of the electric current in a green 

 glass tube (789.), surrounded by a jacket of platina foil, and 

 heated in a charcoal fire. The decomposition began and 

 proceeded very well at first, apparently indicating, according 

 to the general law (679. 697.), that this substance was one 

 containing such elements and in such proportions as made it 

 amenable to the power of the electric current. This effect 

 I have already given reasons for supposing may be due to the 

 presence of a true protoxide, consisting of single proportionals 

 (696. 693.). The action soon diminished, and finally ceased, 

 because of the formation of a higher oxide of the metal at the 

 positive electrode. This compound, which was probably the 

 peroxide, being infusible and insoluble in the protoxide, 

 formed a crystalline crust around the positive electrode; 



