Abstract: A synthetic method for ammonium dinitramide comprising a process for the formation of urea nitrate by reacting urea with diluted nitric acid; a process for the formation of nitrourea by reacting the urea nitrate with sulfuric acid; a process of reacting the nitrourea with a nitration reagent such as nitronium tetrafluoroborate, and then adding ammonia gas to the reaction mixture; and a process of filtering off the resultant by-product of crystals, concentrating its filtrate, adding ethyl acetate to this concentrated filtrate, filtering off the precipitate, concentrating again its filtrate under vacuum, and finally separating ADN as crystals by adding chloroform to the concentrated filtrate.Effects:ADN can be synthesized with the following features: urea as starting material is readily available and is cheaper in price, the process is uncomplicated and more simplified, the operation is safe, and the final product gives a high yield.

Abstract: A lithotriptor is disclosed, which comprises an outer slender tube having an outside diameter small enough to be inserted into the organ growing a stone therein and an inner member disposed inside the outer slender tube. The inner member or the outer slender member incorporates therein an explosive layer or a gas-generating layer, ignition means for igniting the explosive layer or the gas-generating layer, and a closing member for preventing rearward advance of the gas evolved during the explosion of the explosive layer or the gas-generating layer. By the blasting of the explosive layer or the gas-generating layer, the outer slender tube or the inner member is caused to collide with the stone and crush it.