McLaurin relates the story of nitroglycerin, the reluctant lubricant, "Thus far the losses of human life were occasioned by the explosion of great quantities of the messenger of death. The next instance demonstrated the amazing strength of Nitroglycerine in small parcels, a few drops ending the existence of a vigorous man at Scrubgrass, Venango county, in the summer of 1870. R.W. Redfield, agent of a torpedo company, hid a can of nitroglycerin in the bushes, expecting to return and use it the following day. While picking berries Mrs. George Fetterman saw the can and handed it to her husband. Thinking it was lard oil , which nitroglycerine in its fluid state resembles closely, Fetterman poured some into a vessel and sent it to his wells. It was used as a lubricant for several days. Noticing a heated journal one morning, Fetterman put a little of the supposed oil on the axle, with the engine in rapid motion. A furious explosion ensued, tearing the engine house into splinters and partially stunning three men at work in the derrick. Poor Fetterman was found shockingly mangled, with one arm torn off and his head crushed into jelly. The mystery was not solved for hours, when it occurred to a neighbor to test the contents of the oil can. Putting one drop on an anvil, he struck it a heavy blow and was hurled to the earth by the force of the concussion. The can was a common oiler, holding a half-pint, and probably not a dozen drops had touched the journal before the explosion took place. Fetterman was a man of remarkable physical power, weighing two-hundred-and thirty pounds and looking the picture of health and vigor. Yet a quarter-spoonful of nitroglycerine sufficed to usher him into the hereafter under circumstances particularly distressing."
From The Titusville Morning Herald on October 15, 1870, "The use of nitroglycerin has become so common, and the casualties resulting from any accidental explosion of it have been so frightful, that any improvement which adds to the safety of its transportation and storage deserves any encouragement. Mr. Nobel, the most extensive manufacturer of it in the world, whose name is everywhere associated with the improved explosive agents of the day, adopts the practice of mixing it with alcohol. This is said to make it perfectly harmless, so that a rifle ball may be fired into it, or a percussion cap explode in it with perfect safety. The simplicity of this process, and of that which restores its explosive qualities, recommends [it] as much as does the safety of the prepared article."
"If water be added to the solution, the nitroglycerin immediately sinks to the bottom, and is drawn off for use. In the prepared state, it is packed in hermetically sealed cans, thus preventing the evaporation of the alcohol, which would restore its dangerous qualities to the nitroglycerin, and it may be sent to any distance, and in any climate without the risk of explosion.
"The Boston Advertiser says the article prepared by Prof. George Mowbray, at the North Adams factory, in Massachusetts, is transported in a pure but frozen state when it is quite as harmless as it is rendered by the Nobel process. The Lake Shore Nitroglycerin Company also manufactures under Prof. Mowbray's patent."
As revealed in the story Frozen Nitroglycerin, W.P. Granger found out that in its frozen state, nitroglycerin is extremely insensitive. Much nitroglycerin was thereafter transported frozen for safety reasons. The new method described by Nobel was to add ethyl alcohol to the nitroglycerin prior to transport, the alcohol and nitroglycerin being miscible. At the job site, water would then be added to the mixture and the nitroglycerin would settle out in the bottom of the container, the water / alcohol mixture to be decanted off the top, or the nitro drawn from the bottom of the vessel.
Acetone added to nitroglycerin operates in a similar desensitizing manner. The following table summarizes the change in sensitivity for various nitroglycerin / acetone mixtures, given in detonation drop height, for the 2 kilogram weight used in the Bureau of Mines impact test:
NITRO ACETONE IMPACT HEIGHT
100% 0% 16 centimeters
90% 10% 23 centimeters
80% 20% 41 centimeters
75% 25% 60 centimeters
73% 27% 64 centimeters
70% 30% 100 centimeters plus
Note: If you are a bomb squad member, this could be very useful information on your next suspected nitroglycerin call. Take alcohol or acetone to desensitize the nitro and then destroy it in safety. Both ammonium nitrate and C-4 get a 100 centimeter plus rating on the above test, but a 50-50 pentolite mixture (cast boosters) gets a rating of only 29 centimeters. I mention this only as a reminder that cast boosters, which we in the industry use by the millions today, have an impact sensitivity on par with an 90 to 10 nitroglycerin / acetone mix. That being said, I have personally witnessed over 50 instances of cast boosters going through stone crushing plants without detonation, illustrating the practical safety of these devices (not an endorsement of such abuse).
Contact us with questions or comments.
In the late 1940s, DuPont developed a desensitized nitroglycerin product called EL-389, which formulation used dinitrotoulene as the desensitizer. It was almost universally called "red glycerin" and many torpedo companies, including Otto Cupler, made it under license from DuPont. The thirteenth edition of the DuPont Blasters Handbook states, "A rifle bullet will seldom explode it, for example, and detonation has never occurred in numerous fire tests. EL-389-B gives at least as good production as either liquid or solidified nitroglycerin, but reduces the clean-out substantially. The latter is the time required to remove the debris from the well, and represents a large part of the over-all cost of shooting. Reduced clean-out with equal or better production, as compared with LNG (liquid nitroglycerin) or SNG (solidified nitroglycerin, commonly called blasting gelatin), means that EL-389-B has (1) less shattering effect in the immediate vicinity of the hole, and (2) a comparable or possibly greater radius of blasting action. EL-389-B has been particularly successful in the Central and Eastern fields; it also finds application, however, under certain conditions elsewhere."
This essentially spelled the end of the pure nitro days as the D.O.T. and the states demanded the desensitized product be used (perhaps DuPont did some lobbying here). Otto Cupler continued to manufacture and use the pure or white glycerin as it was called, along with red glycerin, until their plant blew up in 1978. Other small torpedo companies located across the country continued to do the same, but closed their doors long before 1978. The Otto Cupler Torpedo Co bought desensitized nitro after 1978 from Independent Explosives in Scranton, Pennsylvania, until their nitro plant blew up in 1989. Today, only the old Hercules Plant (Dyno Nobel), located in Joplin, Missouri, continues to manufacture nitroglycerin for dynamites, but refuses to supply EL-389-B.
Copyright © 2000-2008 The Otto Cupler Torpedo Co. & AnaLog Services, Inc.