The Drying and Weighing of the Oxalate.
It was necessary to dry the oxalate before weighing from fifteen to twenty hours at 150°C. in addition to the twenty hours drying of the whole preparation. At this temperature the last traces of moisture were removed by prolonged heating.
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.