It is usually sold in the form of a stick 20 centimetres (roughly 8 inches) long and 2.5 centimetres (1 inch) in diameter, but other sizes also exist. Dynamite is considered a high explosive, which means it detonates rather than deflagrates.
Another form of dynamite consists of nitroglycerin dissolved in nitrocellulose and a small amount of ketone. This form of dynamite is similar to cordite. This form of dynamite is much safer than the simple mix of nitroglycerin and diatomaceous earth/kieselgur.
Dynamite is predominantly used in the mining, quarrying, and construction industries and has had historical use in warfare, but its unstable nature, especially if subjected to freezing, has rendered it obsolete for modern military use. Dynamite has been replaced for combat purposes by military dynamite, a mixture of TNT, RDX, inert binders and anti-freeze agents. Military dynamite has approximately 60% of the strength of nitroglycerin-based, commercial dynamite. While not technically dynamite, it is called this as a slang term.
Dynamite was invented by Alfred Nobel and was the first safely manageable explosive stronger than black powder. Nobel obtained patents for his invention: in England on 7 May 1867; and in Sweden on 19 October 1867. He originally sold dynamite as "Nobel's Blasting Powder". After its introduction, dynamite rapidly gained popularity as a safe alternative to gunpowder and nitroglycerin. Nobel tightly controlled the patent, and unlicensed duplicators were quickly shut down. However, a few United States businessmen got around the patent by using a slightly different formula.
Over time, the dynamite will "weep" or "sweat" its nitroglycerin, which can then pool in the bottom of the box or storage area. Crystals will form on the outside of the sticks. This creates a very dangerous situation. While the actual possibility of explosion without a blasting cap is minimal, old dynamite is still dangerous.
One of the drawbacks of dynamite was that it was dangerous to manufacture. There were two massive explosions at the Somerset West plant in the 1960s. Some workers died, but loss of life was limited by the modular design of the factory and earth works and plantations of trees that directed the blasts upwards. Pressure from trade unions forced AECI, after 1985, to phase out production of dynamite. The factory then went on to solely supply ammonium nitrate emulsion based explosives that are far safer to manufacture.
In the United States, in 1885, chemist Russell S. Penniman invented ammonium dynamite, a form which utilized ammonium nitrate in addition to the more costly nitroglycerin. These dynamites were marketed with the trade name, "Extra." Ammonium nitrate has 85% of the energy of "straight" nitroglycerin. Dynamite was manufactured by the E. I. du Pont de Nemours & Company, Inc. until the mid-1970s. Other US dynamite makers of the era included Hercules, Atlas, Trojan-US Powder, Austin, and several other smaller firms. Dynamite was eventually phased out in favor of water gel explosives, which is cheaper to manufacture and in many ways safer to handle.