This new smokeless powder, which is adapted for use in arms of all calibres, is prepared from a particu lar type of colloid nitro-cellulose. Such an extension of the employment of this latter body from its original use for detonating purposes, to its new use as a pro gressive explosive, has attracted general attention, and led to a more careful and extended study of the nitro celluloses in general. It is with the view of further extending such study and of possibly preparing the way for the introduction of future improvements in progressive explosives that this book has been pre pared.