232 ON THE OXIDES OF LE.\». 



being dried at the temperature of 300*', weighs ] 12 grains. 

 Hence 100 grains of lead yield 162i graiiis of nitrate of lead. 

 From this we learn that 100 parts of nitrate of lead confift of 

 61 1 lead, 

 383- foreign bodies. 



100. 

 Carbonate of 3. When 112 grains of nitrate of lead (dried at 300°) are 



Jead : white diflTolved in water and mixed with a folution of carbonate of 

 lead, 



potafli, a copious white powder precipitates, which is a car- 



honate of lead. Bergman ihewed long ago, that the white 



lead of commerce is precifely the fame with this carbonate. 



When waflied, colleded on a filter, and dried at 300**, it 



weighs 90 grains. This {hews us that 69 grains of lead yield 



DO grains of carbonate: of courfe, 100 grains of lead would 



yield 1 SOf grains of carbonate. From this experiment we 



learn, that 100 parts of precipitated carbonate of lead are 



conipofed of 



761 lead, 



23-^ foreign bodies. 



100. 

 Carbonate of 4. When 90 grains of precipitated carbonate of lead are ex- 



lead by heat pofed in a retort to a heat gradually raifed to rednefs, the 

 oxide ; 9 lead + acid and water which they contain are driven off, and a yellow 

 J oxigen: coloured oxide remains behind. This oxide weighs 77 grains, 



and contains, of courfe, 69 grains of lead. Hence it follows, 

 that the yellow o5^ide of lead is compofed of 69 lead + 8 oxi- 

 gen, or per cent, of 



89.7 lead, 

 10.3 oxigen. 



100, 

 — very fufible. It is well known that the oxides of lead very eafily melt and 

 run into glafs. This happens in the preceding experiment, 

 unlefs particular care be taken. In that cafe the lead a6ls with 

 great energy upon the retort; but the lofs of weight is the 

 fame, unlefs the heat has been a great deal too high. When 

 the oxide is fufed in an earthen velTel, it covers the furfaca 

 with a yellow glafs, as in the coarfefl: kinds of pottery. In 

 that cafe fouie of the oxide may be difllpatcd, unlefs the pro- 

 pec 



