The weighing of the oxalate was made in the weighing glasses in which it was dried. Two of these glasses had been previously tared against each other, using the lighter as the tare and adding fragments of glass to it until the difference in weight was a small fraction of a milligram. The oxalate having been dried to constant weight, was weighed. It was then poured as carefully and completely as possible from the weighing glass into the crucible and the glass again weighed against its tare. The difference in the two weights gave the amount of oxalate. The glass and its tare were dried and reweighed to determine if the few milligrams of oxalate adhering to the walls of the glass had absorbed any moisture during the transfer of the oxalate. In one experiment a slight difference was detected when a second drying and weighing were made.
The weight of the cadmium oxalate as obtained from the balance was corrected for the difference in specific gravity between the cadmium oxalate and the weights.
The Results.
| At. Wt. Cd. | At. Wt. Cd. | At. Wt. Cd. | At. Wt. Cd. | |||
|---|---|---|---|---|---|---|
| (O=16) | (O=16) | (O=15.96) | (O=15.96) | |||
| (C=12.001) | (C=12.003) | (C=11.971) | (C=11.973) | |||
| CdC₂O₄ | CdO | |||||
| I | 1.53937 | .98526 | 112.026 | 112.033 | 111.746 | 111.753 |
| II | 1.77483 | 1.13582 | 111.981 | 111.988 | 111.701 | 111.708 |
| III | 1.70211 | 1.08949 | 112.049 | 112.056 | 111.769 | 111.776 |
| IV | 1.70238 | 1.08967 | 112.051 | 112.058 | 111.771 | 111.778 |
| V | 1.74447 | 1.11651 | 112.019 | 112.026 | 111.739 | 111.746 |
| Mean, | 112.025 | 112.032 | 111.745 | 111.752 | ||
| Maximum, | 112.051 | 112.058 | 111.771 | 111.778 | ||
| Minimum, | 111.981 | 111.988 | 111.701 | 111.708 | ||
| Difference, | .070 | .070 | .070 | .070 | ||
The values assigned to carbon in the last two columns were found thus—
| When | O = 16, | C = 12.001, | when | O = 15.96, | C = 11.971. |
| ” | O = 16, | C = 12.003, | ” | O = 15.96, | C = 11.973. |
Calculating the atomic weight directly from all the oxalate used and oxide found it would give:
| At. Wt. Cd. | At. Wt. Cd. | At. Wt. Cd. | At. Wt. Cd. |
|---|---|---|---|
| (O=16) | (O=16) | (O=15.96) | (O=15.96) |
| (C=12.001) | (C=12.003) | (C=11.971) | (C=11.973) |
| 112.025. | 112.032. | 111.745. | 111.752. |
There seems about equal evidence for the two values assigned to carbon when oxygen = 16. The value of cadmium as given by this method is therefore 112.025 or 112.032.
As will be seen at a glance this figure agrees much more closely with that of Lenssen than with that of Partridge.