76 CHEMISTRY: BAXTER, GROVER AND THORVALDSON 
The Atomic Weight of Lead — Continued 
SOURCE OP MATERIAL 
GRAMS OF 
PbCU 
GRAMS OF 
Ag 
RATIO 
PbCU: 2Ag 
ATOMIC 
WEIGHT OF 
Pb 
GRAMS OF 
AgCl 
RATIO 
PbCh: 
2AgCl 
ATOMIC 
WEIGHT OF 
Pb 
Average 
Metalline Falls, 
Wash, U. S. A.i 
5.43965 
5.74504 
4.21992 
4.45674 
1.28908 
1.28908 
1.28907 
207.22 
207.21 
207.22 
Average 
Nassau, Germany^ 
6.57216 
5.66330 
5.09849 
4.39340 
1.28906 
1.28904 
1.28905 
207.21 
207.21 
207.21 
Average 
Eifel Mts., 
Germany- 
5.73434 
4.17445 
4.44857 
3.23862 
1.28905 
1.28903 
1.28896 
207.21 
207.21 
207.19 
Average 
New South Wales2 
6.25884 
5.25882 
4.85584 
4.07933 
1.28900 
1.28893 
1.28914 
207.20 
207.19 
207.23 
Average 
New South Wales^ 
7.33227 
6.51699 
1.28904 
207.21 
7.55732 
6.71690 
0.97022 
0.97024 
207.22 
207.23 
Average 
0.97023 
207.23 
Average of all experiments 
1.28905 
207.21 
0.97021 
207.22 
^ Galena; ^ Cerussite. 
Summary of Atomic Weight Values 
PbBr2:2Ag 207.20 
PbBr2:2AgBr 207.18 
PbCUrAg 207.21 
PbCl2:2Aga 207.22 
Average 207.20 
The close agreement of the chloride analyses with those of the bromide 
is very reassuring; for it is difficult to beHeve that any constant error, 
such as hydrolysis of the salts during fusion, could have affected both 
series of results to the same extent. Furthermore it is obvious that the 
different specimens of lead chloride are identical within the limit of experi- 
mental error, and that ordinary lead, if composed wholly or in part of 
isotopes, is astonishingly constant in composition. 
The results of this investigation indicate (1) that lead bromide and 
chloride after fusion in atmospheres containing hydrobromic acid and 
hydrochloric acid respectively are neutral, (2) that no difference exists 
