WHY NITROGLYCERIN?

Mary Beecher Longyear at the Lake Superior Powder Co. on the Dead River, photograph by John M. Longyear, Sept. 9, 1899.

Innovation is no stranger to the Upper Peninsula. The natural resources of the area make it a ripe proving ground for new ideas. The discovery of copper created an opportunity for local miners to experiment with assets like nitroglycerin (nitro). But as is well known, nitro is very unstable. In contrast to nitro’s volatility, black powder, another blasting agent used by miners in the late 19th and early 20th centuries, is relatively stable. Why would miners prefer to use a potentially unreliable explosive over a trustworthy alternative? The answer lies in the easier manufacture of nitro, the cheaper price tag, and the greater efficiency of nitro over black powder.

The easy manufacture of nitroglycerin made it attractive to the companies that supplied the mines at the turn of the century. Black powder manufacture required several days of work. Sulfuric acid was dissolved and heated, and the solution was skimmed to remove impurities. The mixture was cooled, and as it cooled, it hardened. The resulting crystals were then dried and ground into a powder. Charcoal and sulfur were added to the powder, and the ingredients were carefully mixed together. At this step the powder was moistened to prevent explosion, turning it into a paste. Finally, the paste was pressed into cakes and broken up into granular form. In contrast, nitro was easily made in a day. Sulfuric acid was added to sodium nitrate, then poured into earthenware jugs that were placed in ice water to keep the mixture cool (for the mixture to heat up would have been catastrophic). The final ingredient, oil of glycerin, was added to the jugs, air was injected into the mixture, and the resulting nitroglycerin was removed for cleaning. After being cleaned, the nitro was canned and frozen. The nitro was frozen for safer transport, as frozen nitroglycerin was considered almost completely inert. Manufacturing nitro was much more efficient then manufacturing black powder.

With quicker manufacture and fewer materials comes cheaper costs. Nitro manufacturers were able to use fewer men to make more product than the black powder manufacturers. Since the nitro companies were paying fewer workers, buying fewer materials, and producing far more explosives, they were able to charge the mining companies less for their product than black powder companies. The owners of the mining companies, faced with the choice between cheaper nitroglycerin and costly black powder made the obvious decision. As nitro was so much cheaper, black powder soon lost its appeal.

The most compelling reason for the miners to use nitroglycerin was that it was more efficient than black powder. It took 13 pounds of black powder to do the same amount of work as 1 pound of nitro. For explosives to be effective, the miners had to drill a hole in whatever they were blowing up to put the explosive into it; the hole drilled for nitro was 13 times smaller than the hole drilled for black powder. The smaller hole was much easier to drill. Also, the miners had to transport the explosive to the site, usually using pulley systems and horse and cart. With the nitro, they could get 13 times more work done with the same amount of explosive as before. This increased efficiency. Additionally, black powder was not reliable in water, and in the Upper Peninsula, where water is plentiful, this was a problem. Nitro could be used with no issues in water-filled shafts and tunnels. Nitroglycerin was popular with the miners, not just the mine owners, because of its efficiency compared to black powder.

Nitroglycerin was a staple of the mining process in the Upper Peninsula. It is easy to place emphasis on the fatalities inflicted by nitro over the years, but the truth is that those explosions were often caused by carelessness and mishandling. When used properly and carefully, nitroglycerin increased the efficiency of mining operations, including those in the Upper Peninsula.

As beneficiaries of the economic benefits reaped by those same mining companies, we should all be thankful for the miners who risked their lives to provide the country with copper.