Mastering picocoulombs in the 1890s: the Curies' quartz- electrometer instrumentation, and how it shaped early radioactivity history

Résumé En

This paper describes the instrumentation developed by Pierre and Jacques Curie in the 1880s to perform very precise charge and low current measurements. Using this set-up, which is nearly as precise as most present digital electronic charge measurement apparatuses, Jacques Curie established the absorption current law for insulating materials. A detailed analysis is made of the experimental path followed by Marie Curie from the choice of her research subject to her first discoveries, using the same Curie quartz– electrometer set-up. From the Curie ‘‘discovery notebooks'' and a modern reconstitution of this experiment, it is possible to reconstruct what were her main experimental difficulties concerning the measurements of the picoampere leakage currents produced by the radioactive rays. We will underline that the availability for Marie Curie of a precise ready-to-use electrostatic measurement technique played an important, if not decisive, part in her career and her research. A more general issue addressed here is that laboratory techniques are not only a prerequisite of modern scientific work, but in a great part influence knowledge production.