[rckoepke]

The ones I'm thinking of were "nomograms" (thanks to user 'chemeng'). Visually they look like perhaps a very specific subset of "Parallel coordinate" graphs. Definitely more for calculation rather than visualization. Evidently they were popular from around 1890 to at least 1950.

[kortex]

They are still quite useful for predicting boiling points under reduced pressure.

https://www.sigmaaldrich.com/chemistry/solvents/learning-cen...