LEAD. 71 



J. J. Berzelius and F. H. Wollaston : 207 J{. (O = 

 16); 1295 (0 = 100). 

 Berzelius found 16.5 parts carbon di-oxide equal to 83.5 

 lead oxide, whence the value, if C = 75.4. [If C = 12, 

 these figures give lead at 206.67.] Berzelius also determined 

 the composition of the oxide at 7.15 oxygen and 92.85 lead, 

 giving Pb = 207.52 or 1297. {Fhil Trans., IO4., 1814, 20.) 



J. J. Berzelius: 207.12 (0 = 16); 1294.498 (O = 



100). 



Determined by the reduction of a known weight of oxide 



of lead by hydrogen and the weight of the resultant lead ; 



mean of four nearly coincident experiments. [Poggend. 



Ann., 8, 1826, 184. 



— Longchamp is credited in some books with an atomic 

 weight determination of lead. He made none, but only 

 speculated on the composition of minium, taking Berzelius' 

 determination as a basis. {AnnaL de Chim. et de Phys., 34-, 

 1827, 105.) 



J. J. Berzelius : 207.078 (O = 16) ; 129Jf.2J^ (O = 

 100). 

 This value is the mean of six experiments on the reduc- 

 tion of the oxide in a current of hydrogen. The oxide was 

 produced by the decomposition of the nitrate by heat. As 

 this compound reacts upon Pt, the crucible was lined out 

 with a coating of a very basic nitrate, w^hich prevented the 

 lumps of neutral salt from coming in contact with the cruci- 

 ble. The glass in which the oxide was reduced was not 

 attacked. [The third analysis is miscalculated. It should 

 show an atomic weight of 1295.595. The mean is, there- 

 fore, as above, and the extreme difference 2.421,] [Poggend. 

 Ann., 19, 1830, 314.) 



J. J. Berzelius: 207.U (0 = 16); 1294.645 (0 = 

 100). 



In his Lehrbuch, Berzelius selects five analyses made by 

 the above method, three of them the same. These give the 

 above mean, with an extreme difference of 0.704 for = 

 100. [Lehrbuch, 3, 1219.) 



E. Turner : 207.3 (0 = 16). 

 Determined by experiments on the conversion of metallic 

 lead and of oxide of lead into the sulphate by solution in 



