Part 5 (2/2)
When in lumps its apparent density is 01; if twisted into thread, 025; when subjected, in the form of pulp, to hydraulic pressure, 10 to 14
Gun-cotton preserves the appearance of the cotton from which it is made
It is, however, harsher to the touch; it is only slightly hygroscopic (dry gun-cotton absorbs 2 per cent ofelectrified by friction It is soluble in acetic ether, amyl acetate, and acetone, insoluble in water, alcohol, ether, ether-alcohol, nited by contact with an ignited body, or by shock, or when it is raised to a temperature of 172 C It burns with a yellowish flame, almost without sases fore, and consists of carbonic acid, carbonic oxide, nitrogen, and water gas Conited often explodes when previously heated to 100 C
Gun-cotton kept at 80 to 100 C decoo a slow decomposition It can, however, be preserved for years without undergoing any alteration It is very susceptible to explosions by influence For instance, a torpedo, even placed at a long distance, un-cotton The velocity of the propagation of the explosion in un-cotton has been found to be from 5,000 to 6,000 mms per second in tin tubes, and 4,000 in leaden tubes (Sebert)
Gun-cotton loosely exposed in the open air burns eight tiun-cotton may be fired into from a rifle without explosion; but if the thickness of the disc be increased, an explosion un-cotton in mines is very nearly the sahts It requires, however, a stronger detonator, and it gives rise to a larger quantity of carbonic oxide gas Gun-cotton should be neutral to litmus, and should stand the Government heat test--tee 249) In the French Navy gun-cotton is submitted to a heat test of 65 C
(= 149 F) for eleven e of soluble nitro-cotton and of non-nitrated cotton as possible
The products of perfectly detonated gun-cottonequation:--
2C_{12}H_{14}O_{4}(NO_{3})_{6} = 18CO + 6CO_{2} + 14H_{2}O + 12N
It does not therefore contain sufficient oxygen for the complete combustion of its carbon It is for this reason that when used for enerally added to supply this defect (as, for instance, in tonite) It tends also to prevent the evolution of the poisonous gas, carbonic oxide The success of the various gelatine explosives is due to this fact, viz, that the nitro-glycerine has an excess of oxygen, and the nitro-cotton too little, and thus the two explosives help one another
In practice the gases resulting froun-cotton are-- Carbonic oxide, 2855; carbonic acid, 1911; en, 856; water vapour, 2193 per cent The late Mr EO Brown, of Woolwich arsenal, discovered that perfectly wet and uninflaun-cotton could be easily detonated by the detonation of a prie of the dry un-cotton veryexplosive
As a un-cotton is now chiefly used under the forun-cotton and half bariuun-cotton”
The weight of gun-cotton required to produce an equal effect either in heavy ordnance or in sunpowder in the proportion of 1 to 3, ie, an equal weight of gun-cotton would produce three tiunpowder Its rapidity of combustion, however, requires to be enerally used, or such conose, nitrated wood, &c, are used
The initial pressure produced by the explosion of gun-cotton is very large, equal to 18,135 atrammes per square centi 1,075 calories (water liquid), or 9977 cals (water gaseous), but the quantity of heat liberated changes with the equation of deco to Berthelot,[A] the heat of forrms, or 661 cals for 1 kilo The heat liberated in the total coen at constant pressure is 2,633 cals for 1,143 grun-cotton 2,302 cals (water liquid), or 2,177 cals (water gaseous) The heat of decoun- cotton in a closed vessel, found by experie (0023), amounts to 1,071 cals for 1 kilo of the substance, dry and free froun-cotton it must be used in a compressed state, for the initial pressures are thereby increased Wet gun-cotton s much less sensitive to shock than dry Paraffin also reduces its liability to explode, so also does camphor
[Footnote A: ”Explosives and their Power,” trans by Hake and M'Nab]
The substance known as celluloid, a variety of nitro-cellulose nearly corresponding to the formula C_{24}H_{24}(NO_{3}H)_{8}O_{12}, to which camphor and various inert substances are added, so as to render it non-sensitive to shock, may be worked with tools, and turned in the lathe in the same manner as ivory, instead of which ely used for such articles as knife handles, combs, &c Celluloid is very plastic when heated towards 150 C, and tends to becoht beco of the mass, and the consequent evaporation of the camphor When kept in the air bath at 135 C, celluloid decomposes quickly In an experiment (made by M Berthelot) in a closed vessel at 135 C, and the density of the charge being 04, it ended in exploding, developing a pressure of 3,000 kilos A large package of celluloid couard's van on one of the Gerh it is not an explosive under ordinary circumstances, or even with a powerful detonator, considerable care should be exercised in its manufacture
~The Manufacture of Gun-Cotton~--The un-cotton is that of Abel (Spec No 1102, 20 4 65) It orked out chiefly at Stowmarket[A] and Walthaone several alterations These modifications have taken place, however, chiefly upon the Continent, and relate more to the apparatus and machinery used than to any alteration in the process itself The form of cellulose used is cotton-waste,[C] which consists of the clippings and waste material frorease, oil, and other fatty substances by treatment with alkaline solutions, it is carefully picked over, and every piece of coloured cotton rag or string carefully removed The next operation to which it is sub up of themachine, whereby it is reduced to a state suitable for its subsequent treatths, and the fibres opened up and separated from one another
[Footnote A: The New Explosive Co Works]
[Footnote B: Royal Gunpowder Factory]
[Footnote C: Costs from 10 to 25 a ton In his description of the ”Preparation of Cotton-waste for the Manufacture of S states that the German military authorities require a cotton which when thrown into water sinks in two rate; when treated with ether, yields only 09 per cent of fat; and containing only traces of chlorine, linesia, iron, sulphuric acid, and phosphoric acid If the cotton is very greasy, it must be first boiled with soda-lye under pressure, washed, bleached with chlorine, washed, treated with sulphuric acid or HCl, again washed, centrifugated, and dried; if very greasy indeed a preliminary treatment with lime-water is desirable See also ”Inspection of Cotton-Waste for Use in the Manufacture of Gun-cotton,” by CE Munro, _Jour A the Cotton~--This operation is performed in either of tays
The cotton h which a current of hot air circulates, or dried in steam-jacketed cylinders It is very essential that the cotton should be as dry as possible before dipping in the acids, especially if a wholly ”insoluble”
nitro-cellulose is to be obtained After drying it should not contain more than 05 per cent of eneralthe cotton is in steam-jacketed tubes, ie, double cylinders of iron, so and 1-1/2 foot wide The cotton is placed in the central cha 10), while stea jacket, and keeps the whole cylinder at a high temperature (steam pipes may be coiled round the outside of an iron tube, and will answer equally well) By means of a pipe which communicates with a compressed air reservoir, a current of air enters at the bottoh the cotton, and helps to reenerally contains about 10 per cent of moisture and should be dried until it contains only 1/2 per cent or less
For this it will generally have to re cylinder for about five hours At the end of that time a sample should be taken from the _top_ of the cylinder, and dried in the water oven (100 C[A]) for an hour to an hour and a half, and re-weighed, and thein it calculated
[Footnote A: It is dried at 180 C at Waltha chamber]
[Illustration: FIG 10--COTTON DRIER]
It is very convenient to have a large copper water oven, containing a lot of sh to hold about a handful of the cotton, and each co cylinders The whole apparatus should be fixed against the wall of the laboratory, anda small steam pipe from the boiler-house It is useful to have a series of copper trays, about 3 inches by 6 inches, numbered to correspond to the divisions in the stea the cylinders, and a handful of the cotton froht to the laboratory and weighed (a boy can do this very well), placed in their respective divisions of the oven, and left for one to one and a half hours, and re-weighed
When the cotton is found to be dry the botto cylinder is removed, and the cotton pushed out from the top by means of a piece of flat wood fixed on a brooht cases, and is ready for the next operation At so house through which hot air circulates, the shelves being of canvas or of brass wire netting The hot air h the cotton, or the process will be a very slow one
~Dipping and Steeping~--The dry cotton has now to be nitrated This is done by dipping it into a mixture of nitric and sulphuric acids The acids used , that is, the nitric acid ravity of 153 to 152, and should contain as little nitric oxide as possible The sulphuric acid ravity of 184 at 15 C, and contain about 97 per cent of the est acids obtainable should be used when the product required is gun-cotton, ie, the highest nitrate
The sulphuric acid takes no part in the chemical reaction involved, but is necessary in order to combine with the water that is liberated in the reaction, and thus to th of the nitric acid The reaction which takes place is the following:--
2(C_{6}H_{10}O_{5}) + 6HNO_{3} = C_{12}H_{14}(NO_{3})_{6} + 6 H_{2}O
324 378 = 594 108
Cellulose Gun-Cotton