LEAD. 395 



acid, is converted into sulphate of cadmium. It 

 is, therefore, a compound of one atom sulphur 

 and one atom cadmium, and its atomic weight 

 is 9. 



SECT. II. 



OF THE ATOMIC WEIGHT OF LEAD. 



I HAVE already in a former section of this work 

 described an experiment, from which the atomic 

 weight of protoxide of lead is easily deduced. 

 Nitrate of lead crystallizes in white opaque oc- 

 tahedrons, and is quite anhydrous. 2O75 grains 

 of it are just decomposed by 11 grains of anhy- 

 drous sulphate of potash ; and the sulphate of 

 lead obtained weighs exactly 19 grains. Now, 

 these 19 grains contain 5 grains of sulphuric 

 acid ; so that the salt must be a compound of 



Sulphuric acid . 5 

 Protoxide of lead 14 



19 



The salt being neutral, and 5 representing the A / o t xi f eof 

 weight of an atom of sulphuric acid, 14 must lead. 

 represent the weight of an atom of protoxide of 

 lead. 



If it be a compound of 1 atom lead and 1 Atom of 

 atom oxygen, then an atom of lead weighs 13 ; e 

 and that 13 is the true weight of an atom of lead 



