Quartz piezoelectric electrometer sits on the workbench in the Rue
The quartz piezoelectric electrometer sits on the workbench in the Rue Lhomond shed this evening, October 25, 1898. A weight of one hundred grams hangs from the quartz plate. The needle of the electrometer moves across the scale as the mineral sample releases its charge. The stopwatch measures the time required for the needle to pass twenty divisions. This duration is 12.4 seconds. Yesterday, under similar atmospheric humidity, the same fraction of pitchblende yielded a measurement of 12.6 seconds. The difference of two-tenths of a second is not a measurement error. It is a signal of the concentration increasing as the bismuth separation progresses.
Every hour of work is a repetition of this calibration. The method requires a constant equilibrium between the tension of the quartz and the ionization produced by the substance. If the compensation is not perfect, the measurement is only an approximation. An approximation cannot reveal a new element. The fractional crystallizations are tedious. The solution is boiled, cooled, and filtered. The crystals are collected. The remaining liquid is tested. The radioactivity is slightly higher in the crystals than it was in the original salt. This increase is minute. It is a fraction of a percent.
These individual data points are the only defense against the exhaustion of the physical body. The acidity of the reagents has begun to crack the skin on my fingertips. The air in the shed is thick with the fumes of boiling hydrochloric acid. Each measurement taken in these conditions is a single stone in a wall. One measurement proves nothing. A hundred measurements suggest a pattern. A thousand measurements, recorded with the same weights and the same stopwatch, constitute a proof. The phenomenon does not appear all at once. It is a slow accumulation of evidence that eventually becomes heavier than the doubt of the scientific community. The total activity of the fraction is now four hundred times that of pure uranium. I will begin the next purification cycle at dawn.