Dated 1871-1873. From Material relating to experiments designed to measure electromotile forces and electric potential, [1834-1875].

Working notes and rough drafts of hypotheses, methodological narratives, experimental observations and tables of test results compiled by Charles Wheatstone under the general heading of 'electro-motive forces', relating to the utility of employing combinations of elements in battery electrodes, 1871-1873; correspondence between Charles Wheatstone and Richard William Mellingford Higgs, chemist, on the analysis of acid solutions in battery experiments, with Higgs' experimental observations.