1To Benjamin Franklin from Johann Wilhelm Abraham Jaeger, 20 December 1777: résumé (Franklin Papers)
ALS : American Philosophical Society <Frankfurt-on-Main, December 20, 1777, in French: I have a powder mill with twenty-six mixers, and am planning a new one on the model of an oil mill with perpendicular stone mixers, as in the enclosure. Ordinary stone may produce explosions; I experimented with marble and found that it apparently did not. A foreign powder-maker whom I met told me that it is...