An Oxyliquit, also called liquid air explosive or liquid oxygen explosive, is an explosive material which is a mixture of liquid oxygen (LOX) with a suitable fuel, such as carbon (as lampblack), or an organic chemical (e.g. a mixture of soot and naphthalene), wood meal, or aluminium powder or sponge. It is a class of Sprengel explosives.
Oxyliquits have numerous advantages. They are inexpensive to make, can be initiated by a safety fuse, and in case of a misfire, the oxygen evaporates quickly, rendering the charge quite safe in a short period of time. The first large scale deployment took place in 1899 during the building of the Simplon Tunnel, in the form of cartridges filled with diatomaceous earth soaked with petroleum, or an absorbent cork charcoal, dipped in liquid oxygen immediately before use. In another modification, the cartridge is filled with liquid oxygen after placement in the borehole.
One of the disadvantages of oxyliquits is that, once mixed, they are sensitive to sparks, shock, and heat, in addition to reported cases of spontaneous ignition. The power relative to weight is high, but the density is low, so the brisance is low as well. Ignition by a fuse alone is sometimes unreliable. The charge should be detonated within 5 minutes of soaking, but even after 15 minutes it may be capable of exploding, even though weaker and with production of carbon dioxide.
An oxyliquit explosive can be accidentally made by spilling liquid oxygen on tarmac during filling high-altitude airplane systems. The pavement then can become sufficiently explosive to be initiated by walking on it; the oxygen evaporates soon, though.
At first, liquid air, self-enriched by standing (nitrogen has a lower boiling point and evaporates preferentially) was used, but pure liquid oxygen gives better results.