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        "Safety Light Collection",
        "Records Related to Radium Dial Painters"
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    "ocrText": "-6-\n8\nIt will be observed that any one of the instruments can serve for making\ngamma-ray measurements. For each instrument the observed increase in drift\nappears to be directly proportional to the activity of the source. Although\nin the Schmidt instrument the net drift per microgram expressed in divisions\nper second was found to be only about a half of the value for the other two\ninstruments, its natural drift was so low--five small scale divisions in 30\nminutes-and so constant--8 characteristic of the Wulf quarts fiber instrument\ntoo--that its adaptability for gamma-ray measurements should not be questioned.\nThe natural drift of the Lind electroscope used was found to be more fluctua-\nting than that of the Wulf or Schmidt, but in this connection it should be\nremarked that the weather conditions at the time of most of our measurements\n7\nthensy amountry raml cinatent duft.\nwere quite unfavorable for precise measur ements. It was hot and sultry most\nof the time. All of the instruments used were fitted with small drying bulb\nattachments which are indispensable when tests must be conducted on warm,\nhumid days. Keeping the instruments when not in use in a small cabinet pro-\nvided with large trays containing fused calcium chloride reduces very materially\ninsulation troubles.\nEarlier in this report it was stated that per microgram of radium in a\nliving person, distributed fairly uniformly over the entire bony skeleton, the\nnet drift produced in a Wulf quartz fiber instrument was found to be approxi-\nmately 0.0000857 (0.857 x 10-4, divisions per second. When the radium is\nconcentrated on the breast of the inactive subject, the net drift per micro-\ngram-is just,it will be noted, about doubled. Here then we have another re-\nlation for estimating approximately, at least, the amount of radium present in\nliving subjects: Measure first the drift increase of the active subject, and\nthen by trial find the number of five or ten microgram ampoules of radium solu-\ntion fastened on the breast of an inactive subject about the same size which\nwill produce the same drift. The quantity of radium in the active subject will\nbe just about double the sum of the standard radium solutions. This rolation\nprobably holds for any type of electroscope."
}