88 Capt. P. Yorke's Experiments and Observations 



When agitated in a half- filled phial it becomes turbid. The 

 same effect occurs when it is boiled in a glass flask. When 

 left freely exposed to the air without the contact of lead, it 

 deposits the whole, or nearly the whole, of the oxide in the 

 form of the white substance before described. 



23. Becquerel has shown that when solutions of lead or 

 manganese are decomposed by the voltaic battery, the con- 

 ducting wires being of platina, the peroxides of those metals 

 are separated at the positive pole*. I find this to be the case 

 with lead, whether the acetate, the nitrate, or a solution of 

 the oxide in lime water be employed. When the aqueous 

 solution of oxide of lead was thus decomposed, the conducting 

 wires being terminated by slips of platina foil, that at the 

 negative pole was slightly blackened by metallic lead, that at 

 the positive acquired a fine bronze yellow, and the edge of 

 a bit of litmus paper in contact with the foil was bleached. 



24. In my first attempts to ascertain the quantity of oxide 

 of lead which was held in solution by distilled water, the li- 

 quid obtained, as is described (8.), was filtered; but the fil- 

 tered liquid was turbid, and when obtained clear by refiltering 

 it was found on testing it that it no longer contained any lead 

 in solution. This was repeated on a portion of liquid from 

 another bottle, which previously to filtering gave a deep brown 

 with sulphuretted hydrogen, with the same effect. 



25. To obtain the quantity of oxide of lead dissolved by the 

 water, the rods of lead were carefully removed from the bottle, 

 the stopper replaced, and the liquid, when clear, drawn off by 

 a siphon. 



1st trial; 3000 grains of such a solution evaporated with a 

 drop of nitric acid, converted into a sulphate, and thus 

 ignited, weighed '33 grain = -242 oxide. 



2nd, 3000 grains evaporated with a drop of nitric acid in 

 a flask ; the evaporation terminated, and oxide ignited in a 

 platina crucible ; the oxide obtained weighed *245 grain. 



3rd, 5000 grains of the solution was divided into two equal 

 parts : one part was reserved for a subsequent experiment; 

 the other, evaporated as in the last, gave *244 grain of 

 oxide. In the first two trials the quantity of oxide dis- 

 solved is about -r^u tn > in the tnird Tuhv 



26. It is very possible, however, that pure water is really 

 capable of holding a greater quantity of oxide of lead in so- 

 lution than has been here obtained; for it is difficult, if not 

 impossible, to disturb these solutions without occasioning the 

 deposition of part of the oxide in the form of a white powder, 



* Ann. dc Chimie, torn, xliii. p. 380. 



