DS in French, signed “M. Curie,” two pages on two adjoining sheets, 8.25 x 10.5, March 26, 1913. Document headed “Faculty of Sciences of Paris, Laboratory of General Physics, Radioactivity,” with a typed title on the first page, “Certificate No. 101: Radium Dosage by Radiation” [after “radiation” Curie has added the symbol for the Greek letter “gamma” in her hand]. In part (translated): "Nature and Provenance of Appliance: An appliance of solid Ra salt, submitted by Armet de Lisle Company of Nogent sur Marne on March 17, 1913 & returned on March 26, 1913. Measurement Conditions: Gamma [again Curie has penned the symbol for “gamma” in her hand] rays from the appliance were compared to gamma [the symbol for “gamma” is in Curie’s hand] rays from the Laboratory radiation standard. The appliance had not attained its saturation limit which had to be determined by calculation (1). The value given in this Certificate represents the quantity of Radium contained in the appliance providing the material used does not contain any radioactive materials other than Radium and its derivatives. Evaluation is made in Milligrams of Radium Bromide Hydrate…Result: The platinum tube engraved number 4332, The appliance contains 9.76 milligrams…(1) Value thus calculated can be accepted with confidence, but it does not have the same precision as a direct measurement at saturation radiation level which is only attained approximately one month after preparation of the appliance. For an appliance with a platinum tube component, a correction is made in order to take into account the absorption of gamma [once more Curie pens the symbol for “gamma”] rays by the platinum. The Maison Armet de Lisle quote 0.5mm for the platinum thickness.” Signed at the conclusion by Curie as director of the laboratory. In fine condition, with a small edge separation to the horizontal fold.
This intriguing document concerns the measurement of radium for the Armet de Lisle Radium Company, formed in 1904 to produce and refine radium. This was an unusual industry because radium—the most valuable substance in the world—was available only in miniscule quantities and there was no standard method of measuring it. Between 1910 and 1913 Marie Curie and the International Radium Standards Committee settled upon the ‘Curie’ as the standard unit for radiation, named after her late husband and fellow Nobel laureate Pierre. Curie’s laboratory was one of few capable of measuring radium against the standard, which seems to be the purpose of this report. Directly linked to Curie’s pioneering work in radiation, typed and signed much earlier than most form letters we see from her, this is a tremendously desirable piece of scientific history. Pre-certified PSA/DNA.
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