Photo: Creatve Commons License by chefranden
I always thought a grist mill was just another name for a mill that ground flour. Wrong!
In the colonial days, there were several types of mills. A Grist Mill ground corn into meal whereas a Flour Mill ground wheat, rye or buckwheat into flour. Flour Mills were developed later than grist mills because flour was more expensive than meal, and corn was easier to grow and harvest than other grains.
A Merchant Mill was a flour mill where the miller purchased grain from farmers, ground it, and then sold the meal or flour rather than milling grain in return for a percentage of the meal or flour as had been the earlier custom. A by-product of grain milling was Offal, sometimes called "awful". It was the screening, bran and shorts of mostly wheat, and used as animal feed. Not exactly the same as the term 'offal' we use for so-called waste animal parts (even edible parts like sweetbreads, tongue, tripe, heart etc.) although the root definition is the same.
There were Bone Mills that ground bones into meal to be used as fertilizer. Plaster Mills ground local gypsum to be used as fertilizer; it was known as 'land plaster'. The advent of railroads made other fertilizers more economical and the plaster mills dwindled away.
There were also some "manufactories" (mills) of the time. A sumac manufactory would grind sumac leaves and berries (which are high in tannic acids) into a sumac sauce which was widely used in tanning hides. As technology increased there were mills to manufacture woolens (fulling mills), and paper. Distilling, even on a small scale, was a part of life for most of the population.