Powder Mills: An Industry Long Gone

Photograph: One component of a powder-mill, taken from Encyclopédie, published by Denis Diderot, circa1770.

by Bob Wood*

Road names in the area such as Powder Mill Hollow Road, Powder Mill Road, Powder Magazine Road, and Powder Valley bear witness to the extensive, local powder manufacturing of the 18th and 19th centuries. The powder was black powder used for gun powder and blasting. Black powder, incidentally, was not dynamite which had yet to be invented. In the early 20th century, dynamite was called “high-explosive” for its vastly increased power compared to black powder.

Sumneytown, just to our east, was the center of the early powder industry; although there were powder mills scattered all across this area. In 1858 there were eleven powder mills near Sumneytown, mostly along their Swamp Creek (now named the Unami). One source says these mills produced twenty tons of powder daily, although I find that amount suspect. Let’s just say it was a large amount. But wherever railroads, mines or other public works projects needed to remove solid rock, Sumneytown blasting powder was known far and wide for its quality.

The ingredients of black powder are common and the technology of making it was a centuries old European craft brought by the early immigrants. Percentages varied, but basically powder was composed of 75 percent potassium nitrate called “saltpeter,” 15 percent charcoal, and 10 percent sulfur; that’s it. However, powdered and blended together these ingredients will just fizzle; to make them detonate with explosive force took some water power and some doing.

Just when gun and blasting powder was first made here has not been definitely established. There is record of a Fitzinger reconditioning damaged powder for the Revolutionary army; but by 1780 a powder mill was running along the Swamp Creek (Unami), the property having been bought in 1757. The largest powder mill operators in Sumneytown during the 19th century was Lorentz Jacoby and his son.

Powder making was a European craft brought to this area by German immigrants. One informant says that the mill on Powder Mill Hollow Road near Gabelsville used an axle with cams that actuated a row of pounding tubs similar to giant mortars and pestles. This was said to be an extremely primitive European method. However, as it was practiced here, powder manufacturing usually incorporated several widely separated buildings.

The start of the operation was the mixing house. This is where water power was needed. The three ingredients needed to be reduced to almost microscopic particles and tightly compacted into a mechanical bond. In other words they needed to be pressed tightly together. Two large edge running mill stones (later made of iron) were yoked to an axle driven by a vertical shaft powered by a water wheel (see photo). The edge runners revolved in a trough into which the raw ingredients were placed with a little water to make them damp.

Because the edge running stones “wanted” to run straight but were always twisted in a circular motion they had a grinding as well as a crushing effect on the ingredients in the trough. After several hours the material in the trough was compressed into a hard cake.

This cake was delivered to different buildings to be dried and broken into grains of various size, sifted, sorted, polished, packaged and shipped. Conestoga wagons took it by the ton to all points of the compass.

Powder making was a hard and hazardous occupation. There are no mill buildings standing today, only traces of their former sites. Sooner or later they were all destroyed in devastating explosions. In addition to the danger of the powder itself, the structural members were soon impregnated with a fine black dust. It got into everything and inevitably a spark was struck whether by static electricity or otherwise. An unpublished manuscript in the author’s possession written about 1960 notes; “Some of the old people who talked with us about this nearly fifty years ago told some horrifying stories of sights they had seen when they were children after mill explosions which had demolished the mills and scattered parts of the mill workers’ bodies around the scene of destruction….Some said they would never walk up the Swamp Creek [Unami]Road again because of the memories it stirred within them.”

“Prior to 1860, of those buried at Old Goshenhoppen cemetery, 72 were killed in powder mill explosions. Since all those blown up were not buried there and since the industry ran for another forty years with continuing explosions, it is not improbable that at least 200 lost their lives in this manner. This is a large number of fatalities for a community of this size.”

An old newspaper clipping reports that a powder mill explosion near Sumneytown was heard in Norristown. The manuscript’s author continues: “Another evidence of the force of the explosions is an axle bearing made of stone found in the woods on our property about 1500 feet from where one of the oldest mills had blown up. This stone is 7X7X7 and weighs over 25 pounds. It has a highly polished groove about 3 inches wide on the top of which the axle of the mill wheel turned….Consider the explosive force which was generated when the powder mill blew up and hurled this 25 pound stone from under a mill wheel so that it came down in the woods 1500 feet from the demolished mill.”

The woods along the Unami and Macoby creeks near Sumneytown have many, curious, large stone circles now overgrown with trees. Some have speculated they were put there by the Indians for ceremonies. Indeed it has been reported that the fraternal organization, The International Order of Red Men, at Green Lane, would meet in those circles for whatever purposes. But we know that those circles were the sites of charcoal burning pits for the powder industry. This industry and the memory of it now gone along with the Red Men.

* An inspiring Jack of all trades, master of many, Bob Wood serves as Studio B's Gallery Adjunct when he's not busy doing everything else! Writer, artist, potter, historian, and volunteer. Bob began his career as an artist following his retirement from teaching Language Arts. Bob is a popular speaker; local history is his niche. Bob has published four books on local history.

More News from Boyertown

• Hoagies: a Love Story Mikę Strzelecki and Friends tour local sandwich shops reputed the best in Hoagie World ,explore styles of hoagie-making, and satisfy a longing for their favorites.
• Linda Jacobs' Childhood Memory Captured in "That Stormy Night" A prized memory with her father was created for Linda Jacobs during a "dark and stormy night."