436 
PROFESSOR J. W. MALLET OR' THE ATOMIC WEIGHT OF GOLD. 
Experiments with Gold Salt and Zinc. 
Cliaracter of 
gold used. 
Charactei' of 
gold salt. 
Gold 
precipitated 
Hydrogen, at 0° C. and 760 mm. 
H 3 -drogen equivalent to gold. 
Experiment. 
Oorrespondi g 
to total zinc. 
Obtained from 
residual zinc. 
Vol. at 0° C. 
and 760 mm. 
Weight. 
I. 
A, h 
AuCq 
grm. 
10-3512 
c.cm. 
177^44 
c.cm. 
-23-34 
c.cm. 
= 1756-10 
erm. 
= T5768 
11. 
A, h 
AuBi-g 
8-2625 
14-28-99 
-28-61 
= 1400-.38 
= -1-2574 
III. 
A, h 
AuCk 
8-1004 
1393-43 
-18-56 
= 1374-87 
= -12345 
IV. 
C 
Aucq 
3-2913 
582-82 
-24-18 
= 558-64 
= -05016 
V. 
C 
AuBi’g 
3-4835 
606-20 
-15-27 
= 590-93 
= -05306 
VI. 
D 
AuBi’g 
3-6421 
643-31 
-25-20 
= 618-11 
= -05550 
In considering- possible causes of constant error in the experiments of this last 
series it seems most likely that they would affect the exact determination of the 
weight of the precipitated gold, either by meclianical loss of some minute particles of 
the metal, tending to lower the atomic weight, or by incomplete washing out of the 
zinc salt, with an influence in the opposite direction. Any failure to remove the last 
traces of moisture from the hydrogen was, I think, effectually guarded against, at any 
rate within such limits as would have sensibly affected the resulting atomic weight; 
and any error due ro retention of hydrogen in solution by the liquid must also have 
been inappreciably small, in view of the precautions taken and the close similarity of 
conditions in the experiments with zinc alone and with zinc and the auric salt. 
Calculation of Residts. 
In calculating the atomic weight of gold from the data furnished by the experi¬ 
ments which have been described, I have thought it best to conform to the most 
general usage of those who have lieen working on questions of this sort of late years, 
so as to facilitate comparisons with the results of others. Hence, although the atomic 
weight has been calculated separately from the figures of each experiment reported, 
the value deduced from each series has not been taken as the arithmetical mean of the 
separate lesults, nor has tlie probable error of these or of the mean been calculated by 
the metimd of least squares, as w-as done in my paper on the atomic w^eight of 
aluminum, but, instead, the general result for each series has been obtained, as in the 
calculations of Meyer and Seubert, from the aggregate quantities of the materials 
employed, though I am by no means convinced that this mode of reckoning is in all 
cases sound in principle, giving, as it does, weight to each experiment in proportion to 
the quantity of material employed. 
The atomic weiglits assumed for the other elements involved are those which have 
been most generally accepted in calculations of this kind, based for the most part on 
