LEAD. 399 



Deutoxide of lead does not seem capable of 

 entering into any chemical combination ; it is, 

 therefore, in the present state of our knowledge, 

 comparatively insignificant as a chemical sub- 

 stance. 



3. The peroxide of lead is a flea brown Atom of 

 coloured powder, which was discovered by lead. 

 Scheele. It may be obtained by digesting ni- 

 tric acid on red lead. A portion of the deutox- 

 ide is reduced to the state of protoxide, and dis- 

 solves in the acid, while the oxygen given off by 

 it uniting to another portion converts it into 

 peroxide. If the deutoxide be pure, it is evident 

 from the experiment stated above, that just one 

 half of the lead is dissolved and the other half 

 converted into peroxide. 



I found long ago, that 100 grains of this ox- 

 ide, when exposed to a red heat, left 91 grains 

 of protoxide.* Now, if the 9 grains of loss be 

 considered as oxygen, it will follow from this ex- 

 periment, that peroxide of lead is composed of 

 100 lead + 18*34 oxygen, or of lead 13 + oxygen 

 ^384. But when I made these experiments I 

 was not aware that metallic oxides are apt to re- 

 tain water : the peroxide which I employed had 

 been merely dried in the open air, and conse- 

 quently, was not quite anhydrous. The loss of 

 weight was partly water and partly oxygen ; 



* Nicholson's Journal, VIII. 288. 



