Ogg ON THE OXIDES OF LEAD* 



comes milky, and depofits a white powder. This pOwder 

 does not difappear, though the folution be heated boiling hot; 

 but the liquid acquires the property of diffolving an additional 

 quantity of the ("alit, without depofiting any more white pow- 

 der. Boiling water difTolves the fait without any fimilar de- 

 pofition. Hence I think we may conclude, that the white 

 powder is owing to the prefence of fome carbonic acid in the 

 cold water, and that our fait in this refped refembles acetate 

 of lead. 

 The fait depo- 3. When 30 grains of the fait depofited during the boiling 

 filed in the boil- ^f j-j^g j^^^j jj^ ^j^g nitrate, were cautioufly heated to rednefs, 

 yeitow oxide and they melted into a yellow mafs, which weighed 2i>.5 grains. 

 an under propor- xhe lofs of 5.5 grains muft be afcribed to acid and water. 

 ' Hence this fait is compofed of 



81.5 oxide, 



18.5 acid and water. 



100.0 

 Thefe 24-. 5 grains of oxide being diflblved in nitric acid, 

 yielded 35 grains of common nitrate of lead (dried at 300°). 

 But 35 grains of nitrate contain 24- grains of yellow oxide, 

 ■which fcarcely differs from the quantity diflblved. From this 

 experiment it feems to follow, that the fait in queftion contains 

 only yellow oxide, and that it differs from common nitrate in 

 containing a fmaller proportion of acid. But it will be faid, 

 perhaps, that the oxide of the fait abforbed oxigen from the 

 nitric acid during the application of the heat, and was thereby 

 oxidized up to the ftate of yellow oxide, 

 ns alfo the cryf- ^' Twenty-three grains of the needle-form cryflals were 

 tals do. dilfolved in water and decompofed by carbonate of potafli. 



The carbonate had the common appearance, and, when dried 

 in 300", weighed 2i grains. But 24- grains of common car- 

 bonate contain about 211 of oxide, and ought therefore, when 

 diiTolved in nitric acid, to yield about 3l| grains of common 

 nitrate of lead (dried at 300**); and, upon trial, I found this 

 to be the cafe very nearly. The oxide in the needle-form 

 cryftais then is the yellow ; for there is no apparent courfefrom 

 •which, in the above experiment, oxigen could be drawn. And 

 if this be the cafe with the needles, it muft be fo alfo with th© 

 fcaly cryftals ,• for the two lalts are obvioufly the fame. 



5. Sixty- 



