• N THE OXIDES OF LEAD. ' Q^^ 



per precautions are laken. It deferves attention, tiiat when Singular fail. 

 carbonate of lead is flovvly heated in a glafs retort till it begins 

 to melt, the melted portion has a fine yellow colour, while 

 the colour of what remains in the flate of a powder is a dirty 

 pale brick-red; whereas in a platinum crucible llie melted 

 portion is red and the unmelted yellow. 



5. From the preceding experiments it follows, that the Cotrefted ele- 



yellow oxide of lead contains 10.3 per cent, of oxigen. Mr, "'^P'* °^ ''^^ 

 T. n 1 . . 1 • 1 . - . carbonate. 



rroutt has deduced nme per cent, as the proportion of oxigen, 



from his experiments. This refult does not differ much from 



mine. If I have committed an error, the oxigen I think is 



rated too high; for the lead which I ufed contained If per 



cent, of antimony, the oxides of which have much more oxigen 



than the yellow oxide of lead. Perhaps we fliail come nearer 



the truth by taking the mean of the two refults: we may 



therefore confider the yellow oxide of lead as compofed of 



90| lead, 



9l oxigen. 



100. 



6. The preceding experiments enable us to ftate the confti- Comp. parts ni- 

 luents of nitrate of lead as follows : fate of lead. 



1. Nitrate dried onBlotting- 



Paper. 



66 yellow oxide, 



3-t acid and water. 



100 



2. Nitrate dried at 300^. 



6S.5 yellow oxide, 

 3 1 .5 acid and water. 



100.0 



&c. 



They give us alfo the precipitated carbonate of lead, dried 

 at 300°, as follows : 



86 yellow oxide, 



14 acid and water. 



100. 

 The native carbonate of lead contains about \6 per cent, of 

 carbonic acid. Precipitated carbonate then either contains 

 lefs acid than native, or it lofes a part at a low heat. It is 

 well known that carbonates, when in cryflals, frequently con- 

 tain more acid than when in the ftate of powders. 



7. Yellow oxide of lead is a powder of a lively yellow colour, CharaSters and 

 taftelefs, infoluble in water, but foluble in fixed alkalies and J;^'uJ;''J^°/J''' 



acids. 



