On account of insurance restrictions imposed on freight companies it is often impracticable to ship gun-cotton in its dry state. When this is the case the gun-cotton primers are issued wet and are packed in the spare exercise torpedo-cases from which, on receipt aboard ship, they are to be removed and dried and then stowed in the glass jars for dry primers. * * * * * A Torpedo Outfit, consisting of 24 Service, Pattern D. Torpedoes, 12 Exercise (10 filled, 2 empty), Pattern D. Torpedoes and 4 jars of dry gun-cotton for primers will contain, approximately, the following amount of gun-cotton:— WET GUN-COTTON. 24 Service Pattern D,} {1296 2-inch blocks; or 1200} Torpedoes }={ 2-inch blocks and 384 }wet = 818.1 lbs. } { ½-inch blocks } dry. 12 Exercise (10 full,} {60 2-inch blocks; or 50 } 2 empty) Pattern D,}={ 2-inch blocks and 40 }wet = 37.9 lbs. Torpedoes } { ½-inch blocks } dry. } {1356 2-inch blocks; or 1250} Total wet gun-cotton }={ 2-inch blocks and 424 }wet = 856 lbs. } { ½-inch blocks } dry. DRY PRIMERS. 6 each of {16 ½-inch blocks;} {96 ½-inch blocks;}dry = 15.2 lbs. dry. {or 4 2-inch blocks }={or 24 2-inch blocks} ----- Total equivalent of dry gun-cotton in outfit 871.2 lbs. dry. The wet charge of a torpedo, Pattern D, is composed of blocks two inches thick. The primer charge is composed of blocks ½ inch thick, if there be any on hand; otherwise, of blocks 2 inches thick. The 2-inch block contains 10.1 oz. and the ½-inch block 2.5 + oz. of dry gun-cotton. CARE OF GUN-COTTON AND DETONATORS. =The Gun-Cotton Magazine= must not be located near the boilers or engines, nor where the temperature of the magazine will equal 105° F. for any great length of time. The magazine should be aired frequently. Avoid as much as possible exposing any box or case containing gun-cotton, dry or wet, to the direct rays of the sun for any length of time, as the temperature inside the box can, in this way, be raised to a point considerably above that of the open air and this temperature will be maintained for a considerable time after the exposure. The diurnal changes of temperature will not affect gun-cotton, wet or dry, provided that the cases or boxes containing the gun-cotton are not exposed to the sun. The detonating charges of dry gun-cotton are designated “primers,” and the fulminate of mercury igniter as the “detonator.” The primers of dry gun-cotton supplied to each ship are packed in glass jars with tight covers to exclude moisture. Strips of blue litmus-paper are placed between the blocks of dry gun-cotton.