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The National Radium Emanator (ca. 1923-1930) |
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| The National Radium Emanator, an extremely
sophisticated device, was produced sometime in the 1920s by National
Radium Products Company of New York City. The label indicates a patent
date of 1923.
The photo to the right shows the emanator alongside its carrying case. The photograph below is a close-up of the instructions that are clipped to the inside of the door of the unit. |
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Operation of the Emanator: The glass bottle (lower left corner of the unit in the top photo) was filled with tap water and then mounted in the holder as shown in Figure 1 of the instructions. The holder was then rotated to an upside down position so that radon gas bubbled through the water thereby charging it. Next, the holder was returned to its original position so that the bottle, now filled with radioactive water, could be removed. Finally, the water was transferred to a drinking glass and consumed or used for some other purpose such as watering plants. The Source: Based on the measured exposure rates around the emanator, we estimated that it contained a substantial fraction of a millicurie of Ra-226 - 0.5 to 1.0 mCi or so. To reduce the exposure rate to a level that would allow the unit to be put on display, we had to remove the source. The latter consisted of a dried deposit on the inside of a series of glass tubes and vessels in the back of the case.
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The only reference I have found to the National Radium Emanator is a newspaper account from the 1950s describing the discovery and disposition of one of these units. Size: ca. 14" x 12" x 8" Case: Wood (mahogany?) Exposure Rate: ca. 5 - 8 mR/hr above background at one foot prior to the removal of the source. |
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