Processing Limestone to Make Plaster
"Lime production in the 19th Century needed several natural features to facilitate production of such materials."
The heating of limestone to produce marketable material, such as quicklime, involves a process of burning, roasting, or calcining natural limestone cobbles or blocks. Lime production in the 19th Century needed several natural features to facilitate production of such materials. A natural limestone ridge or vein of the appropriate stone type near the surface for quarrying first had to be located, as well as large quantities of local wood for fuel. Later when railroads were developed, coal was introduced to the lime firing process, so access to coal sources also became a necessity.
On the present day property bordering Carrollton Road, McCain’s ancestors David Rogers Harley and Erastus Hubbard began their partnership lime kiln operation in 1857. The 30-acre original tract borders the Wabash & Erie Canal, 1,000 feet behind a current home of McCain descendants.
Here's what these brothers-in-law said about operating their 30-foot-tall “pot kilns”—
“A kiln is round on the inside and often square on the outside. The upper cylinder comes down to a narrower neck just above the firebox at the bottom of the chimney. The cooling zone is down below the firebox. The firebox comes in from two sides. You stack wood as close as you can and as high as you can reach. Then you dump the rock in at the top.”
“Next, you light the fire. In about 36 hours you should be able to make your first draw of lime. You take out the ashes and drop the lime into the cooling basin. From then on the lime sticks and you have to trim it with a cutting bar around the edges. The lime sits in there like a cone. You trim the edges and drop it straight down. It has to cool six hours below the firebox before you can pull it out. Even at that time it will be so hot that it will be transparent.”
“When you get ready to draw the lime you let the fire die down. Then when you get ready to cut the kiln you draw the lime. You take a couple of big sticks of wood in there and pry just over the edge. Then you take your bar and trim it. The work was very hazardous, and you had to keep from getting burned.”
“Firing a kiln is a very technical job. Really it takes an expert to fire a kiln. If they relaxed and rested their eyes too much the kiln would tell on them and go to “rocking.” We had the best people you could ever assemble—they could do anything. We had little to work with except our hands for the most part.”
Restoring the Kiln
"Today this Hubbard and Harley kiln site is being restored. It is on the National Register of Historic Places."
The placement of masonry lime kilns took into account the distance from the stone quarry site to the kiln processing area and the distance from the kiln to the nearest transportation source. These kilns also served local needs and a road paralleling the Wabash & Erie Canal connected with the site. These kilns also served regional markets; therefore, the canal accessed a long-distance form of transportation—the canal and later railroads. In 1857, Hubbard and Harley sent lime in barrels as far as New York City via animal powered canal boats from their own dock beside these kilns.
Since most lime products were of the “bulk” variety, profits from operating a lime industry rested on the movement of large shipments of raw lime products on a regular schedule. The perishable and sometimes flammable (volatile) nature of most lime products also limited production to available shipping resource types. As an example, railroads could transport lime faster than canals or wagons, which opened up more markets for lime production operations. Thus, the second generation, known as the “Harley Brothers,” (Charles and George) opened a new more efficient kiln just north of Delphi in 1888. Their office was on Carrollton Road just across from the Ice Plant that bordered the present Delphi Golf Course. Shipping after the turn of the century was more efficient with the use of the Belt Railroad that connected the old Monon and Wabash railroads.
The advance of the "patented" kilns (continuous burning 11 months per year) on this site reflects these second-generation Harley's desire to increase the efficiency of the human labor force as well as increase production output in a shorter amount of time. The three side-by-side "modern" kilns allowed the operators to stagger the firings, which would produce more lime with fewer workers and man-hours.
In the high point of production in north Delphi, 22 lime kilns produced over 500,000 bushels of burned lime per year. McCain kilns were across Carrollton Road, and by 1871 all kiln owners in north Delphi formed a new corporation—Delphi Lime Company. The first general manager was Daniel McCain. He was in that position until he died in 1884. Daniel McCain's son, Luther, married Charles Harley's daughter, Helen, in 1904 bringing these two-family names together.
The corporation had over 100 men working at the quarry and kiln sites and another 25 year-round in the woods harvesting logs. Later, the logs were brought to the kiln site on the old Monon Railroad from land 5 miles south of Delphi because by the 1890s the local source of timber was depleted. The Harley brothers owned the “Harley Switch” where logs were loaded.
The most common byproduct of burning lime was quicklime, which was used to make plaster and mortar for building construction. Higher quantities of calcium carbonate in the limestone resulted in higher quality plaster and mortar material. Delphi's limestone was even better because it also included magnesium carbonate that made a superior spreading and drying product sought out by professional craftsmen of the time.
Because burned lime absorbs water over time, it is labeled as a perishable product that must be used within a set period of time or it becomes useless for construction purposes. By adding sand to the mix, bonding between the sand and the lime results in a hardened product (either mortar or cement) that keeps its shape over time. Harley's lime products were “packaged” in barrels made in the Samuel Grimes' defunct canal hotel known as "Grimes' Folly" just behind the present-day McCain home.
Another lime-based product was whitewash, which was quicklime that had been saturated with water and then mixed with glue. Lime was also processed into similar whiting materials, such as “bleaching powder,” and was used in the paper industry to break down rag pulp. Delphi was also a producer of high-quality paper made from rags. Other uses for lime included hair removal in the tanning industry, as an ingredient in soap making, and as a fluxing agent in glass making and iron ore smelting. Another common use for lime was as a neutralizing agent or “fertilizer” for agriculture.
The perishable nature of the processed lime necessitated a quick, reliable, and protected means of transport to consumer. The presence of the railroad within walking distance of a number of the more efficient continuously burning kilns of the late 1800s provided Delphi with the ideal combination of high-quality raw materials and transportation routes to larger markets. The lime kilns that were constructed to exploit this combination of transportation and natural resources led to Carroll County's economic heyday.
Today this Hubbard and Harley kiln site is being restored. It is on the National Register of Historic Places and can be visited from the new Interpretive Center by taking the Towpath Trail north 3/8 mile to the restored 1873 Iron Bridge over the canal at the point where the old Belt Railroad once crossed. The once majestic 30-foot tall kilns were at the northeast corner of the bridge where there is an interpretive sign at the trail's junction.
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