Peter J. Starley

Warwickshire RFD 156

Gun Powders, Black Powders,
Nitro Propellants And All Reloading Materials

Gunpowder Mixing Machine, No. 4

Here the saltpetre, charcoal, and sulphur, usually in the proportion of 75, 15 and 10, are mixed be revolving the drum 40 revolutions per minute, and the flyers inside the drum at 120 revolutions.

Mixing goes on for about five minutes.