Standard Chemical Company, in 1918. Since ther,
-roduction of the Company has been as follows.
1913... “rams
1914. .
1915. .
1916. .
1917.........
1918.........
1019..........
1920. .......... Cea
1921 to April 1st... ........

the

Total................. 71.8
Radium preparations in the United States are spoken
of and measured in terms of Radium element. Until
recently in European scientific circles, Radium has been
referred to in the terms of Radium bromide. Crystalline
radium bromide when pure, contains 53.6 per cent of
Radium element. This fact and the method of measurement
 of Radium preparations in Europe prior to the
adoption of the International Radium Standard, had not
a little to do with the earlier unsatisfactory work with
Radium. There was no common standard. The original
method of measuring Radium consisted in comparing iis
activity with that of Uranium. During the fourteen
years this system of measurement prevailed, scientific men
spoke of Radium as “two million times more active than
Uranium.” Trained minds, of course, understood that
what was meant was that the quantity of electrical energy
emitted in the rays of the Radium, small though it was,
was two million times greater than that contained in the
rays from Uranium. Such a ratio of comparison was
entirely unsuitable for use especially with small quantities,
and about 1912, by common consent, Madame Curie was
asked to prepare what would be an International Radium
Standard. This is deposited at Paris. Duplicates are in
the leading capitals of the world, and Radium preparations
are now measured by comparing the electrical energy
carried by the gamma rays from the preparation to be
measured with the energy carried by the gamma rays of