The ferrosilicon process for the generation of hydrogen
A 1920 technical report on the ferrosilicon process for generating hydrogen, issued through the NASA Technical Reports Server and drawn from a government-era engineering study. Its pictures are plain line graphs plotting hydrogen yield, heat of solution, cost and weight against time and alkali quantity, with labelled curves, gridded axes and handwritten-style captions. A designer could take from them the clean, restrained vocabulary of early scientific charts: thin dark curves on fine grids, stepped axes and compact figure captions.
