2g^ ON THE OJflDES Of LEAD, 



ficids, The alkaline folutions have a yellow Ungc ; but the 

 acids are mod frequently colourlefs. It readily melts when 

 healed, and forms a yellow, femitranfparent, brittle, hard glafs. 

 It does not lofe oxigen gas when healed. In violent heats a 

 porliou of the oxide is diffipated. When kept heated in the 

 open air, its furface becomes brick-red. When mixed with 

 metallic lead it runs, according to Proufl, into a green glaze. 

 Yellow oxide by g. yhe yellow oxide may be obtained diredllyfrom the nitrate 

 Se'nhratef """ P^ ^^^^> ^ expofing that fait to a fufficient heat ; but the lofs 

 of weight fuft^ined is ufually greater than it ought to be. I 

 fufpect that this is one reafon why Prouft found fo fmall a 

 proportion of oxigen in yellow oxide. One hundred grains 

 of nitrate of lead (obtained by evaporation) were put into a 

 I'mall Wedge wood crucible furnlthed with a lid, and enclofed 

 in a common earthen-ware crucible. They were expofed for 

 half an hour to an intenfe red heat in a wind-furnace. The 

 fait was converted into a very hard, yellow, brittle glafs, 

 nearly opake : It had fuftained a lofs of 40 per cent, or about 

 -fix per cent, more than it ought to have loft. On breaking this 

 glafs to pieces the reafon of this became obvious : It contained 

 a great number of globules of lead reduced to the metallic 

 Hate, fome of them of confiderable fize. From this experi- 

 ment we learn, that lead is reducible directly from the nitrate 

 merely by the apphcalion of heat, without adding any com- 

 buflible matter, 



II. Suppojed firfi Oxide. 



Aflies of lead, When lead is kept melted in the open air, it Is foon covered 

 or fuppofed firft ^j^j^ ^ jj^^^ coloured powder, formerly called the aJJies of 

 yellow oxide an4 lead. When this powder is heated fufficienlly, it melts into a 

 nictallic lead. greenifh yellow glafs, In which globules of lead may be de- 



te6led. Mr. Prouft has (liewn, that ihefe alhes are a mixture 



of the yellow oxide of lead with lead In the metallic flate. 



They do not, therefore, conflitule a peculiar oxide. 



Neither is the xchite oxide of the French chemifts enlilled to 



a place among the oxides of lead ; being In all cafes nothing 



more than the yellow oxide combined with an acid, ufually 



the carbonic, 

 prouft's oxide But Mr. Prouft, in his obCervatlons on the Connoijfances Chi- 

 !^'^^fh"''"f T ^'"?"^* *f Fourcroy, has mentioned the method of forming an 



oxide of lead containing lefs oxigen than the yellow. When 



lead 



