Up to the present time the investigations have been confined to explosives used in coal mining, because the Act of Congress establishing the Testing Station has thus limited its work. Accordingly, it is not possible to compare, on the systematic basis just mentioned, the explosives generally used in rock work. It is probable that, if the Bill now before Congress in regard to the establishment of a Bureau of Mines is passed, work of this character will be undertaken, and the tables of explosives now prepared will be extended to cover all those intended for general mining and quarrying use. Data of such character are unobtainable to-day, and, as a result, a considerable percentage of explosives now used in all mining operations is wasted, because of their lack of adaptation to the materials being blasted. It is well known, for example, that when an explosive of high percussive force is used in excavating in a soft or easily compressed medium, a considerable percentage of its force is wasted as heat energy, performing no other function than the distortion and compression of the material in which it is fired, without exerting either an appreciable cracking or fissuring effect, or a heaving or throwing of the material. Owing to lack of information in regard to the exact relationship between the percussive and the heaving force in particular explosives, this waste, as compared with the quantity required for the work with a properly balanced material, will continue; but it is to be hoped that it will soon be possible to give the mining and quarrying industries suitable information in regard to the properties of the various explosives, so that the railroad contractor and the metal miner may have the same simple and exact means of discrimination between suitable and unsuitable explosives that is now being provided for the benefit of the coal miner.