ABSTRACT

One of Claude Bernard’s teachings in his Introduction to the Study of Experimental Medicine (1865) was the importance to physiologists of following up anomalies in their vivisections. There is no evidence that Crookes ever read Bernard in French, yet he shared the Frenchman’s enthusiasm for following up observations that appeared to go against the tenor of the investigation, seeing these as signals or signposts for further investigations that led to deeper understanding of phenomena. It was one such strange anomaly encountered during Crookes’ eight-year-long investigation of the atomic weight of thallium that was to lead him away from analytical chemistry into the realms of fundamental molecular physics in the 1870s and that crowned his international reputation as a man of science.