Researches upon the atomic weights of cadmium, manganese, bromine, lead, arsenic, iodine, silver, chromium, and phosphorus . d by the salt could be reduced to a constant percentage,which could be determined in separate experiments. The complete drying of the salt by fusion was not permissible because of de-composition of the arsenate at temperatures in the neighborhood of its fusingpoint. During the drying of the arsenate the quartz tube was surrounded witha cylinder of thin platinum foil and was contained in a hard-glass tube connectedwith an apparatus for furnishing a current of pure dry air
Researches upon the atomic weights of cadmium, manganese, bromine, lead, arsenic, iodine, silver, chromium, and phosphorus . d by the salt could be reduced to a constant percentage,which could be determined in separate experiments. The complete drying of the salt by fusion was not permissible because of de-composition of the arsenate at temperatures in the neighborhood of its fusingpoint. During the drying of the arsenate the quartz tube was surrounded witha cylinder of thin platinum foil and was contained in a hard-glass tube connectedwith an apparatus for furnishing a current of pure dry air. The hard-glass tubewas heated by means of two aluminum blocks 15 cm. by 13 cm. by 5 cm., oneplaced above the other, the upper surface of the lower block and the lower sur-face of the upper being suitably grooved to contain the tube. The blocks werebored to contain a thermometer, the bulb of which was located near the middleof the tube. This oven (fig. 4) could be readily maintained at constant temper- ^ Pub. Car. Inst., No. 69, 69(1907); ,2g,Ss3; Zeit. anorg. Chem.,55, 80. 78 RESEARCHES UPON ATOMIC. Fig. 4. — Solid aluminum drying oven. ature within a very few degrees by means of a Bunsen flame. We are indebtedto Dr. Arthur Stabler of the University of Berlin for the suggestion of thismethod of heating. In order to purify and dry the air it was passed through a tower filled withbeads moistened with dilute silver-nitrate solution, through a tower filledwith small lumps of solid potassium hydroxide, then through 3 towers filled with beads moistened withconcentrated sulphuric acid,and finally through a tubefilled with resubUmed phos-phorus pentoxide. The apparatus was con-structed wholly of glass, withground joints, and was simi-lar to that shown in fig. i,page 8. After being heated, thequartz tube was transferredto a desiccator and was allowed to come to the temperature of the balancecase before being weighed. The quartz tube was then placed upon hard-glass
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