ON THE OXIDES 0¥ LEAD. 285 



lead is boiled in afolutlon of nifrate of lead, the liquid gradually 

 afliimes a yellow colour, and, on cooling, depofits'cryfials in 

 fcales. Thefe cryftals, according to Proud, contain (he oxide 

 in queftion : But his conclufions, as far as appears, were 

 formed from the fingle experiment related. He does not feem 

 to have decompofed the fait, nor to have examined its bafe. 



1. When 100 grains of nitrate of lead are dilfolved in water. The experfmentr- 

 and boiled in a phial with a cylinder of lead (weighing 64|; 

 grains), the metal foon lofes its brilliancy and is covered with a 

 white cruft, while the liquid affiimes a yellow colour. The 

 boih'ng was continued (water being added as fall as it evapo- 

 rated) till the liquid feemed to exert no farther adion on the 

 lead. The cyhnder being then taken out and weighed, was 

 found to have loft 44- grains. From this we learn, that 100 

 grains of nitrate of lead diflblved in wafer, are capable of 

 uniting with 44- grains of lead, or almoft half their weight. 

 The whole, however, was not dilTolved. A bluifli-grey pow- 

 der fell to the bottom, and increafed in quantity as the cylinder 

 diminilhed. If thefe 4-1- grains were oxidized at the expence 

 of the yellow oxide of the nitrate, we (liould have a new oxide 

 containing much lefs oxigen ; and it would be ealy to alfign 

 the proportion of its conftitueuts ; for 100 grains of nitrate 

 contain 66 grains of yellow oxide, co'mpofed of 59-^ lead and 

 6| oxigen : Therefore the new oxide contains 5V} -J- 4i lead 

 and d| oxigen, or, per cent. 



94 3 lead, 

 6.7 oxigen. 



100.0 



But it is extremely unlikely that the 44 grains of lead fhould 

 receive the whole of the oxigen necellary to enable them to 

 difiblve from the oxide, while an excefs of nitric acid is pre- 

 fentin the folulion. Let us therefore examine the new fait, 



2. When the folution cools, it depofits thin fcaly cryfials of Depofition of 

 a light yellow cohur: They have the fame fweet aHringent J'^'^^^yJ^*^^ •»/ 

 tafte as common nitrate, but are lefs foluble in water. U thefmall needles by 



yellow liquid which remains be farther concentrated, it depo-^^P' ^^hite 

 ■' " , deprif. of carbo> 



fits, on cooling, fmall needles of a pale yellow colour, not nate by cold 

 unlike/«^flr of lead. Their tafte is fweet and aftringent ; they water. 

 are not altered by expofure to the air. When thrown into 

 cold water they fall to the bottom, the liquid gradually be- 

 comes 



