=Shell Fillers.= High explosives for shell fillers. Up to the present explosive “D,” trinitrotoluol and picric acid are the principal high explosives which fulfill the requirements as shell fillers. Explosive “D” on account of its great insensitiveness to shock is used in armor piercing projectiles and also in field gun and howitzer shell. It is detonated by a fuze. Trinitrotoluol is used in submarine mines and in general demolition work as it is much easier to explode than explosive “D.” =Table of Explosives.= The following table gives a good idea of the principal explosives in use in our service and the characteristics of each: High Purpose. or Low. Name. Propelling charge in guns. L Nitrocellulose, smokeless powder. Bursting charge, projectiles. H Picric acid, explosive “D” (powder form) Trinitrotoluol. Blank, saluting charges. L Black Powder. Re-inforce charges, primers. L Black Powder. Base charge, shrapnel. L Black Powder. Time trains, fuzes. L Black Powder. Igniting charges, cannon. L Black Powder. Charges, submarine mines. H Trinitrotoluol wet guncotton. Igniting elements, fuzes H Fulminate of mercury, chlorate and primers. of potash (potassium chlorate).