These kilns were very popular and productive in the later part of the 19th but were doomed by the technology of the early 20th century. They were used to burn off the carbon dioxide from limestone which eventually became a powder used for fertilizer and other applications. The kiln shown here is all that remains of durable unit that sits beside the mainline of the Bel-Del RR, formerly the Pennsylvania RR that ran from Trenton, NJ to Stroudsburg, PA. The railroad was built in 1852 and remains a Phillipsburg steam tourist excursion line today. There is an effort by some historical societies to fix and preserve what's left of these unique kilns.