ABSTRACT
The period from the 1880s onwards saw international attempts to introduce agreed standards of measurements in science. Because there were no agreed values of atomic weights or an agreed standard of measurement with respect to hydrogen or oxygen, the American chemist F.W. Clarke suggested that an International Committee of Atomic Weights should be set up in July 1899. Clarke was an experienced observer and compiler and since 1892, at the request of the American Chemical Society, he had drawn up a recommended list of atomic weight values. Crookes had always published these in Chemical News. In comparing tables published by different chemists in different countries, Clarke had found his task burdensome because very different oxygen standards were in use: 15.96, 15.88 or 16.00. Concerned by the same difficulty, German chemists had already set up a European-based standards committee in 1898, and under the leadership of Wilhelm Ostwald this committee had rapidly reached the conclusion that everyone should adopt the standard O = 16. This was agreed upon in November 1899, when Clarke’s international committee was formed of elected members of the various national chemical societies.1 The committee agreed to publish an agreed list of atomic weight values every year.
