In an old John Wayne movie John has Walter Brennan throw a stick of dynamite at the bad guys and John shoots it with rifle and sets it off. In the Quick and The Dead Russel Crowe sets off some dynamite that they hid near the clock tower by shooting it.
Is that all it would take?
Dynamite is just a stable matrix for nitro, so yes, I’m pretty sure that a rifle shot would set it off, especially the formulation they used in the 19th century. Now, I don’t know.
Dynamite is meant to be stable and safe. It is nitro is a base that was originally made of Fuller’s Earth. The Fuller’s Earth sucked up the nitro and kept it from being set off by the blink of an eye. Instead a sharp jolt (as from a blasting cap) sets it off.
The old stuff was far from perfect. If it was left alone, the nitro would come out of the matrix and pool in the waxed paper covering, that was a Bad Thing. You had to flip the boxes every so often to keep this from happening.
(By the way, I wonder if real dynamite is even used nowadays, with all the neato new things we got now.)
Ya got me. The last time I was around straight dynamite was 40 years ago on the family farm, blasting stumps with my uncle. Of course, back then you could buy it at the local hardware store. At least in farm country.
according to this forum - yes
http://community.discovery.com/eve/forums/a/tpc/f/9401967776/m/7291985509
“Real” dynamite is still available, but it’s not the composition you describe, which was Nobel’s original formula of nitroglycerin, diatomaceous earth, and sodium carbonate. (The standard composition was 40% nitroglycerine, and the level of power and brisance is still used as a relative measure for low-grade high explosives.) The more modern composititon uses nitrocellulose as a stabilizer rther than diatomaceous earth. Because there are more stable and less expensive but functionally compounds, there are only a few facilities that still make dynamite, and there are other formulas which have surpassed nitro-dynamite in popularity. Dynamite, however, is very nonabsorbant of water, unlike PETN or TNT-based blasting gels, and so has application in underwater use like blasting a new canal or water channel. (Composition-4, a very popular military plastique explosive, and similar RDX-based commerical explosives are also very resistant to water, but they are a much higher grade of explosive and not as readily available to the public.)
To the O.P.'s question: virtually all explosives are shock sensitive to a degree–there are a few that require a bicompositional primer or catalyst to make them sensitive, but these aren’t widely used–and the #8 blasting cap has become the standard for detonation sensitivity. A rifle shot on original dynamite formula might very well set it off, and could possibly do so under the right circumstances with newer compositions. I don’t think this would be a reliable way of detonating it, though; unless it is backed up by something hard, as it seems quite possible that the bullet could just cut through the material without making enough of an embedded shockwave to effect detonation. I’d say that it’s almost certain that you couldn’t cause C4 or Semtex to explode in this manner. Pure liquid nitroglycerine, however, can be set off by merely letting a drop of it fall a dozen feet or so (or less if you’ve allowed impurities in the form of the more sensitive nitric esters to form) and could readily be exploded in such a fashion.
In general, commerical explosives are sufficientlly shock-insensitive that even large localized mechanical impulses won’t cause detonation. However, dropping a large mass of it from a great height will likely set it off even if it is allegedly shock-insensitive. As part of a preparation for an air launch test I was peripherally involved in, the Air Force dropped a surplus solid rocket motor to see if the Class 1.3 propellent, normally considered shock insensitive and which will–by unintended experience–take a shot from a high powered rifle without igniting. Dropped from 20,000 feet, it cerrtainly does spontaneously light off with a very brilliant and powerful detonation.
Anyway, the method demonstrated in the movies described by the o.p. just might work, but it would be unreliable, and as usual you shouldn’t take anything you see in cinema for reality, especially the flashy, orange-black mushrooms you usually see emerging from explosions on film.
Stranger
If you didn’t flip the boxes, could the dynamite become so unstable that it might explode at the slightest disturbance? In an early episode of Lost, some of the castaways trek out to an old wrecked ship to recover explosives. The explosives turn out to be dynamite – very old dynamite. One of the castaways is killed when a stick of dynamite explodes in his hand, ironically while he is in the middle of a lecture about how to handle dynamite safely. Could such a thing happen in real life?
Yep. The nitro would migrate to the bottom of the boxes (which were lined with waterproof stuff) and pool there. I would imagine that is the sort of surprise that could change your whole life.
Even pure nitroglycerine is not that sensitive; that is a Hollywood invention (or perhaps an invention of Henri-Georges Clouzot in the excellent thriller The Wages of Fear). However, nitroglycerine which is less than pure can become increasingly unstable, particularly if inferior grades of nitric acid were used in the manufacture. It is more likely that these unstable compounds will eventuallly vaporize off, leaving only a mildly acidic binder and filler, and that the dynamite will become intert rather than unstable, but I suppose that it’s possible in a humid environment that it might combine with and be suspended into condensed water. I’m not saying it would be a wise thing to pick up a piece of old, sweaty dynamite, mind you, but I also wouldn’t base my escape plans on its explosive capability.
It did make for a great scene, though, especially with the teacher harping on and on about being a “red shirt”, how the main characters have all the best supplies and shelter, and so forth…and then he gets blown up just to demonstrate how dangerous the dynamite is. (I’m still not clear, after that, why they took the explosives with them; it seemed pretty clear to me that their chances of surviving a return journey were slim to none, but it’s still about the least nonsensical plot device in the show.)
Stranger
A great scene in the overlooked movie Sorcerer like that. But of course long-neglected, unturned TNT would yield long-neglected, unstable nitro.
Nitpick: trinitrotoluene (TNT) is not nitroglycerine. In TNT, toluene (a benzene ring) is the backbone for the resultant molecule; in nitroglycerine, glycerol (which is not a ring) forms the structure. This gives it very different properties; TNT is a yellowish, slighly oily solid, whereas nitroglycerine is a clear viscous liquid. Under normal conditions, TNT is relatively stable, to the point that shells and bombs packed with it function reliably even after twenty or thirty years of storage, and doesn’t require a binder (though it is often mixed with another explosive compound or a binder to make it more pliable). Nitroglycerine compounds are not nearly this stable, and tend to break down and/or evaporate from the binder compounds they’re mixed in. In any case, TNT won’t give you nitroglycerine, and if it did break down I think the result would be relatively inert isotoluene compounds.
Stranger
Longer than that, since several French farmers meet their maker every year by plowing over unexploded WW1 ordinance. Thats pushing 90 years.
In Scandinavian countries, they still occasionally uncover WWII era Soviet mines that have been suspended in ice and snow for decades. But I wouldn’t want to rely on the stability of these. The US Armed Forces, however, have artillery shells in operational stockpile that are more than twenty years old, and they cook off a random selection each year to assess aging and reliability. I suspect other nations probably have active munitions nearing twice that age.
Stranger
Back to the OP’s question about detonating dynamite with gunfire. 30+ years ago I tried this experiment. Myself and some other teenage pyromaniacs acquired an entire crate of dynamite. We had no caps or fuse but, based on Hollywood, knew we only needed to shoot the stuff.
For the rest of the summer we tried to get this to work. We went around wiring dynamite to trees or rocks and shooting it with a variety of calibers. We used everything from .22 up to .44 magnum and the only result we got was silvery dust spread all over the place. Not once did we ever get even a partial detonation. We used a good bit of our case of dynamite trying to get this to work. Likewise dropping rocks on it from any achievable hight did not cause it to detonate.
Based on my own experience, you have a better chance of winning the lottery than you do of setting off dynamite with a rifle. The problem is that my experience proves nothing and the very next time I tried this it might have detonated.
Regards
Testy
Would it be possible to detonate pharmaceutical nitro? If I hammered one of those little pills on a hard pavement, as we all did with caps when we were little, would I get a small explosion? What if I dropped a glass bottle of the pills from a 20 foot height onto a hard surface?
This always made me wonder about nitro. It’s an explosive, yet it’s taken internally. It’s like being prescribed dynamite pills. Before reading this thread, I didn’t even know that nitro is the explosive part of dynamite.
Based on Testy’s experience, it sounds like something MythBusters should look into…
Spectre
The pharmaceutical nitro is occasionally administered in patches and I have heard that these can go off if the patient is hit with one of those high-voltage heart-starting machines. The explosion is more startling than dangerous. Very little actual nitro in those. This may very well be an urban legend, I certainly have no personal knowledge of it happening.
Nitro (or nitrates in general) dilates blood vessels and can give people serious migraine headaches. Breathing the smoke from a dynamite explosion is supposed to be a real bad idea because of this. Of course, some heart problems need the blood vessels dilated so it is a useful thing.
There is a story (Again, it could be an urban legend) of people working in explosives factories during WWII. Supposedly, they had a lot of headaches while they were working there and when they quit, they had a lot of heart attacks. This may be a UL but it makes sense if you think of nitro dilating the blood vessels and then having them all constrict when the nitro is gone.
Regards
Testy
My grandparents had a crate of Dynamite stored away for blasting stumps. They had this crate for many years, stored it in the outhouse behind their cottage. One of my early memories is of my grandma very carefully pouring the liquid that seeped out of that old Dynamite out of the crate and onto the ground.
Even then (I must have been eight years old) I thought maybe this wasn’t such a great I idea. I asked granny “is that safe”? Her reply: “a lot safer than letting it collect in the crate in the outhouse”.
My grandparents would never have dreamed of simply disposing of it - if something was useful, they saved it. Don’t know what happened to that dynamite, I sure hope someone got rid of it - the cottage belongs to my aunt now, but she’s built a new house on another part of the property and it has been more or less abandoned - it could be that stuff is still there.
Khadaji
After I posted that it occurred to me that if you poked a hole in the dynamite stick and shoved a cap in there you could probably get it to go off fairly easily by shooting it. I’d think this would be especially true if you were using those old mercury fulminate caps.
I’d love to see this on Mythbusters. Great idea.
Regards
Testy
Malthus
I recently talked with a US EOD guy and he had been involved in the clean-up of exactly that kind of area. He just mentioned what a pain it was and I didn’t really question him on it.
I used to know a lot of farmers that had dynamite and other things in their sheds and barns. One guy I met had three grenades in a barrel of straw. These were the old WWII “pineapple” type and when they were setting in that straw they looked like extremely militant eggs. He didn’t actually want the things anymore but was unsure what to do with them. We finally dumped them in his stock pond.
Regards
Testy