Chapter IV

GUN-COTTON.—HOW PACKED.—STOWAGE.—CARE.—INSPECTION AND DRYING.

PACKING AND STOWAGE OF WET GUN-COTTON.

Each Service Torpedo, completely filled with wet gun-cotton, is packed in a rough box for transportation and stowage. The Exercise Torpedoes, ten filled with wet gun-cotton and two empty, are packed six in a box.

Each filled torpedo has attached to its case a tag on which is marked the gross weight of the torpedo in pounds and ounces, the initials of the Superintendent of the Gun-cotton Factory and the factory number of the charge from which the contained gun-cotton is taken.

When received on board ship the cover on which the address is marked is to be reversed. The torpedoes are then stowed in the magazine in a manner similar to that now employed in stowing shells.

MARKS ON BOXES.

+-----------------------+------------------------+
| PAT. D. TORPEDO, | PAT. D. TORPEDOES, |
| SERVICE. | EXERCISE. |
| | |
| = .... LBS. DRY G. C. | = .... LBS. DRY G. C. |
| | |
|(_Factory No. of_ | (_Factory No. of_ |
| __Charge._) | _Charge._) |
+-----------------------+------------------------+

PACKING-AND STOWAGE OF DRY GUN-COTTON.

The glass jars for dry primers, filled with dry gun-cotton, are put in wooden cases, painted white, fitted with sliding covers as described on p. 13. The cases are marked “DRY GUN-COTTON PRIMERS. NOT TO GO BELOW.” They are packed in a rough box for transportation.

When received on board ship the cases containing the jars are placed in different parts of the ship, but are never to be stowed below the water-line.

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.

The glass jars will be kept in their wooden cases. The jars and cases are a part of the permanent outfit and must be cared for and returned. Dry gun-cotton is never to be stowed below the water-line, but it may be carried under any deck above the water-line, care being taken that the glass jars, in their wooden cases, are not within 10 feet of each other, nor in the vicinity of the galley or other fires, nor in the immediate vicinity of the guns of the battery.

In removing from their cases the glass jars holding the dry gun-cotton never expose them to the sun, as the glass may act as a lens and cause the ignition of the gun-cotton.

All other primers will be furnished wet, and packed in the torpedo cases.

As the stock of dry primers becomes reduced, a suitable time and place will be selected for replenishing the stock, by drying, according to the rules for drying gun-cotton, the blocks removed from the torpedoes in priming them.

The detonator has a charge of 35 grains of fulminate of mercury. Detonators are placed in circular wooden blocks, bored to hold eight each, each block being put in a tin box. These tin boxes should never be put below the water-line, but kept in a dry place on the upper decks, and not in the immediate vicinity of the galley or other fires, of the battery, or of other explosives. _All loaded detonators are painted red_, and the tin boxes containing them are also painted red and marked on top “DANGEROUS.” Great care should be taken to grasp the box by the bottom when lifting or carrying it for, if held by the top only, the bottom, with its block, may slip out.

INSPECTION OF GUN-COTTON.

_Weekly—all dry gun-cotton._
_Monthly—all dry gun-cotton._
_Quarterly—all wet gun-cotton._

INSPECTION OF DRY GUN-COTTON.

=Weekly Inspection.=—_The dry gun-cotton primers must be inspected weekly._ This can be done without opening the jars, by observing the condition of the blocks and the strips of blue litmus-paper placed between them.

In the event of any serious decomposition having taken place, the gun-cotton will be found more or less covered with pasty, yellow spots, the jar will be filled with brownish red, highly acid fumes and the litmus-paper will show a decided red color. In this event the gun-cotton may be thrown overboard, but even when in this extreme condition there appears to be little danger of immediate explosion and, if desired for use, this gun-cotton may be wet with the alkaline solution (p. 45), until it has increased 30% in weight, and used as wet gun-cotton. No serious risk will attend this operation. No gun-cotton should be thrown overboard except when a board of experts has pronounced it to be in the condition above described. This is essential, as considerable valuable gun-cotton has been condemned and destroyed and a sense of insecurity has arisen in consequence of errors in inspection.

It frequently occurs that the blue litmus-paper becomes faded by exposure in the jars, but no danger is to be apprehended in consequence.

If the litmus-paper has become reddened, but no fumes or pasty spots are observed, the blocks should be lifted out by the loose ends of the tape and placed on a perfectly clean, dry piece of blotting-paper. Then untie the tape and separate the blocks, being careful not to touch them with the fingers. (A perfectly clean, dry crash towel may be used in handling the blocks.) Remove the strips of litmus-paper, insert freshly moistened strips in their places and tie the tape as before. After an hour‘s interval examine the ends of the strips of litmus-paper. If they have become reddened, wet the blocks with the alkaline solution (p. 45), until they have increased 30% in weight and use them as wet gun-cotton.

If the moistened litmus strips have not become reddened after one hour‘s exposure, replace the blocks in the jar, close it tight and replace it in its box.

=Monthly Inspection.=—Even if no change is observed in the litmus-paper at the weekly inspections the test just described, with freshly moistened blue litmus-paper strips, is to be applied to all dry gun-cotton once each month and this constitutes the _monthly inspection_. If the test shows the gun-cotton to be acid, the gun-cotton should be wet with the alkaline solution (p. 45), until it has increased 30% in weight, and then used as wet gun-cotton.

INSPECTION OF WET GUN-COTTON.

=Quarterly Inspection.=—The wet gun-cotton is packed in the Service and Exercise cases and contains from 30% to 35% of water. The gross weight of gun-cotton and case is marked upon each case. These cases are to be separately weighed every three months and any loss in the gross weight made up by the addition of pure water poured through the filling-hole, which should then be carefully closed.

PRECAUTIONS TO BE TAKEN IN INSPECTION.

Do not handle the gun-cotton with the bare hand. Never touch litmus-paper with the bare hand. Blue litmus-paper may become reddened by the acid substances exuded from the skin. Litmus-paper should always be handled with the forceps provided in the Chemical Box.

Always moisten the litmus-paper before making the test, using the distilled water provided in the Chemical Box. Hold the litmus-paper strip in the forceps, dip one of the glass rods, provided in the Chemical Box, in the bottle of distilled water and then apply the moist rod to the paper. The litmus-paper must be moist, only, and not reeking with water. Should the supply of water in the Chemical Box be exhausted, water distilled on board, or fresh rain water, may be used, provided it first be tested and found free from acid reaction.

Make a comparative test to prove that there is, or is not, an acid reaction. As blue litmus-paper may sometimes become slightly reddened when moistened with distilled water only, a comparison should always be made by taking two pieces of fresh blue litmus-paper and moistening one with distilled water and the other with dilute vinegar.

Always examine the test papers by white light. Litmus-paper will present a reddish appearance in any apartment that is shellacked or colored; the examination of test papers should therefore be made only in a light room or in the open air.

Do not mistake iron rust for pasty yellow spots. Gun-cotton sometimes becomes rusted in the course of manufacture, or from the cases in which it is packed. The rust does no harm.

Avoid unnecessary handling of the blocks, as they are apt to flake and crumble.

ALKALINE SOLUTION.

The alkaline solution referred to above is made by dissolving four ounces of dry carbonate of soda in one gallon of rain or distilled water. When it is found necessary to wet dry gun-cotton this solution may be poured into the jar holding the blocks.

RULES FOR DRYING GUN-COTTON.

Wet gun-cotton primers can be dried by any of the following methods:—

1. Exposure in a steam-drier.
2. ” to calcium chloride. (Ca Cl₂).
3. ” in a dry atmosphere.

The quantity of dry gun-cotton primers that are furnished being very small, the stock should be replenished as fast as used by drying the wet blocks removed from the torpedoes in priming them.

DRYING BY EXPOSURE IN A STEAM-DRIER.

The steam-drier must be located above the water-line, remote from fires and lamps and where it will not be subject to disarrangement. Its supply of steam is to be derived from a suitable part of the steam-heating apparatus of the ship or from any other convenient source of low-pressure steam by piping fitted at the Navy Yard.

The blocks to be dried are separately weighed, the weight of each marked on it with a soft lead-pencil (never putting labels of any kind on the gun-cotton) and then strung on the rods, with the iron washers strung between adjacent blocks, and placed in the baskets of the drier. The baskets are put in the drier, the door is closed, the thermometer put in place, steam is turned on and the ventilating openings are adjusted.

The baskets, rods and washers must be kept free from dirt and oil.

The temperature of the drying chamber must not exceed 100° F.

After each day‘s heating carefully remove and weigh each block, re-mark it and proceed with the drying.

This process should be continued until the blocks no longer lose weight, when all but a small percentage of moisture will have been expelled. It has been found by experiment, however, that gun-cotton containing as much as 13% of water can be relied on to detonate, the service fulminate of mercury detonator being used.

When the drying is complete remove the blocks from the drier, place them, while still warm, in the glass jars, with strips of blue litmus-paper between them and close the jars tight. They will then be stowed and inspected as dry gun-cotton.

If the process of drying is not continuous the blocks must be kept in a powder tank, closed tight, when the drier is not in operation.

DRYING BY EXPOSURE TO CALCIUM CHLORIDE (Ca Cl₂).

This method requires:—5 lbs. calcium chloride (Ca Cl₂), 1 empty powder tank and 3 baking pans.

The calcium chloride (Ca Cl₂) is cheap and can readily be obtained from any dealer in chemicals; it must not be confounded with chloride of lime or bleaching powder (CaO₂Cl₃). The latter has a strong odor of chlorine and, if used instead of the calcium chloride (Ca Cl₂), might cause decomposition of gun-cotton. The former is odorless and has no bleaching properties. To distinguish whether the substance has any bleaching properties, stir a small portion in an equal volume of water and immerse a piece of blue litmus-paper in the mixture. If the color disappears from the paper when dry (turning white), the substance is chloride of lime or bleaching powder (CaO₂Cl₂) and must not be used.

The powder tank can be readily procured on board ship; care must be taken that it closes easily and air-tight.

The baking pans should be of such a size that three of them will cover the bottom of the tank when placed alongside of each other; made of stout tin, free from solder, and 5 to 6 inches deep.

Divide the calcium chloride between the three pans and place these pans, which must be clean and free from oil or grease, in the oven of the galley and allow them to remain there until all traces of moisture disappears. Stir the calcium chloride occasionally with a clean metal rod to expose the lower particles. Break it into pieces the size of a pigeon‘s egg. When all traces of moisture have disappeared remove the pans to a dry place and allow them to cool. The calcium chloride must not be put in the tank, nor the gun-cotton exposed to it, while warm. Place the tank in some suitable location where it will not be disturbed and, when the calcium chloride is cooled, place the pans in the bottom of the tank and lay over them a copper sieve, tinned copper wire being the best. Then place the blocks to be dried on the sieve and close the tank. Open the tank every 3 or 4 days, weigh the blocks, marking the weight and date with a soft lead-pencil on them and dry the calcium chloride as before. Continue this until the blocks have ceased to lose weight. While the calcium chloride is drying, the blocks are to be kept in the tank, which must be closed to exclude the moisture in the air. When they have ceased to lose weight stow them in the glass jars for dry gun-cotton primers, taking care to lay between them strips of blue litmus-paper, and treat them according to the rules laid down for dry gun-cotton.

This operation is independent of the condition of the atmosphere and only requires the care mentioned.

DRYING BY EXPOSURE IN A DRY ATMOSPHERE.

String the blocks to be dried on a wood, brass or copper rod or pipe, which must be free from dirt and oil, or place them on a shelf made of wire netting, separating the blocks from each other to expose all surfaces freely to the air; suspend the rod or shelf in some suitable place not in the vicinity of the galley or other fires, where the blocks will be freely exposed to the air, and be under cover.

Expose the blocks only when the atmosphere is dry; at all other times keep them in an empty powder tank, in the immediate vicinity of the place selected for drying, kept closed to exclude moisture. Weigh the blocks every two days, noting the date and weight with a soft lead-pencil on them. Continue the drying until the blocks show no loss of weight for two consecutive weighings; then place them in the glass jars, with strips of blue litmus-paper between, and treat them according to the rules given for dry gun-cotton primers.

This plan can only be carried out in dry climates.

Avoid unnecessary handling of the blocks, as they are apt to flake and crumble.

MISCELLANEOUS DATA.

Dimensions of gun-cotton blocks

length 2.9 inches.
width 2.9 ”
height { 2.0 ” for full sized blocks,
{ 0.5 ” for primer blocks.

Diameter of detonator hole = ⁷/₁₆ inch.

Pressure applied to blocks in the final press = 6800 lbs. per square inch.

Average gravimetric density of compressed dry gun-cotton = 1.287.

Average weight of one cubic inch of compressed dry gun-cotton = 325 grains, = 0.743 oz.

Weight of water added to each pound of dry gun-cotton when issued to the service as wet gun-cotton (approximately 35%) = 0.35 lb. = 5.6 oz.