Activation of hydrocarbons and the octane number
A 1939 technical report from the NASA Technical Reports Server, a scientific paper on activating hydrocarbons and their octane number, probably written for engineers and chemists studying fuels. The pictures are plain line drawings of laboratory apparatus: glass tubing and flasks, a cylindrical vessel with a cross-section, and a sectioned tank with a fitted mechanism, giving a designer little beyond the schematic look of early technical diagrams in black ink on white.

