. Technical paper. the exhausted electroscope on one T^T^xro^ Q « i^v, , side and to the outside air on the other side. After JIGUKE o.—o UlpJllirlC- acid microdrying bulb, the Capillary ciids insidc the rubber connectionswere broken air was allowed to pass over the ore into the electroscope,the tube being heated over a Meker burner IJ inches in diameteruntil the Jena glass completely collapsed. This treatment, as thefollowing table shows, gives complete de-emanation. Air was passed directly over the ore tlirough a drying bulb into theelectroscope—a procedure that is justified only when thoriu
. Technical paper. the exhausted electroscope on one T^T^xro^ Q « i^v, , side and to the outside air on the other side. After JIGUKE o.—o UlpJllirlC- acid microdrying bulb, the Capillary ciids insidc the rubber connectionswere broken air was allowed to pass over the ore into the electroscope,the tube being heated over a Meker burner IJ inches in diameteruntil the Jena glass completely collapsed. This treatment, as thefollowing table shows, gives complete de-emanation. Air was passed directly over the ore tlirough a drying bulb into theelectroscope—a procedure that is justified only when thorium is ab-sent. That the ore contained no thorium is supported by two experi-mental observations—first, that the electroscope, after the radiumemanation is pumped out, returns in a few hours to its normal naturalleak, whereas it would not do so if contaminated by active deposit ofthorium emanation; and, second, the results obtained by the ignitionmethod agree well with those obtained by the solution method, in. ELECTKOSCOPIC DETERMINATION OF RADIUM. 17 •which the emanation was always permitted to stand in a gas burettefor 10 minutes before being passed mto the emanation chamber. Itseems certain, then, that there is little or no thorium in the following table is a comparison of results obtained for anumber of carnotite ores by using the four methods just of these results shows that the solution method and theignition method give concordant results, whereas the fusion methodand the fusion-and-solution method give low results. For this reasonthe two latter methods were not employed in obtaining any of thedata reported in Table I. Comparison of results of dijfferent methods for de-emanating carnotites. Numberof ore. Total emanation in curies X lO^ by method of— Solution in1:1 HNO3. Fusion with NasCOs andKsCOs. Ignition. Fusion andsolution. 2 4 13 14 15 16 17 2
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
