Part 11 (1/2)

[Illustration: FIG 31--MR M'ROBERTS' MIXER FOR GELATINE EXPLOSIVES]

The best way to keep the tee tank of water raised upon a platfor, which is automatically supplied ater, and into which steah a piece of cork and floated upon the surface of the tank will give thethe temperature

When the jelly in the tanks has become semi-transparent and the cotton has entirely dissolved, thened for this work, and are built in iron, with steel or bronze kneading- andto requirements

A suitable machine for the purpose is that known as the Nito-Universal Incorporator, shown in Fig 30, which has been specially constructed by Messrs Werner, Pfleiderer, & Perkins, Ltd, afterof explosive materials, and is now almost exclusively adopted in both Governe M'Roberts'[A]

31, is still used in some factories for dynamite jelly

[Footnote A: See _Jour Soc Chenite, or gelatine dynamite, it is at this point that the proper proportions of wood-pulp[A] and potassium nitrate should be added, and the whole well redients are thoroughly incorporated

[Footnote A: Most of the wood-pulp used in England is obtained from pine-trees, but poplar, lime, birch, and beech wood are also used It is chiefly imported as wood-pulp The pulp is prepared as follows:--The bark and roots are first res then sawn into boards, from which the knots are reh a machine which breaks the, which are then crushed between rollers These fragments are finally boiled with a solution of sodium bisulphite, under a pressure of about 90 lbs per square inch, the duration of the boiling being from ten to twelve hours

Sulphurous acid has also been used Pine-wood yields about 45 per cent

and birch about 40 per cent of pulp when treated by this process The pulp is afterwards bleached and washed, &c

Birch Beech Lime Pine Poplar

Cellulose 5552 4547 5309 5699 6277 per cent

Resin 114 041 393 097 137”

Aqueous extract 265 247 356 126 288 ”

Water 1248 1257 1010 1387 1210 ”

Lignine 2821 3914 2932 2691 2088 ”]

The following analysis of woods is by Dr H Muller:--Theseht into the house and the machine worked by means of a belt at twenty to thirty revolutions per reased and examined, and the explosive elatine hly incorporated, and neither particles of nitrate or wood meal can be detected in the mass, it should be transferred to wooden boxes and carried away to the cartridge-es

[Illustration: FIG 32--PLAN OF THE BOX CONTAINING THE EXPLOSIVE, IN M'ROBERTS' MACHINE]

The application of heat in the lycerine is absolutely necessary, unless solycerine, such as acetone, acetic ether, methyl, or ethyl-alcohol (They are all too expensive, with the exception of acetone and e scale) These liquids not only dissolve the nitro-cellulose in the cold, but render the resulting gelatine compound less sensitive to concussion, and reduce its quickness of explosion (as in cordite) They also lower the teealed, ie, they lower the freezing point[A] of the resulting gelatine

[Footnote A: It has been proposed to mix dynamite with amyl alcohol for this purpose Di-nitro-mono-chlorhydrine has also been proposed]

The finished gelatine paste, upon entering the cartridge huts, is at once transferred to the cartridge- un- a shaft and screw The revolutions of the shaft cause the thread of the screw to push forward the gelatine introduced by the hopper on the top to the nozzle, the apex of the cone-shaped case, froelatine issues as a continuous rope The nozzle is of course of a diae required

[Footnote A: G M'Roberts, _Jour Soc Chem Ind_, 31st March 1890, p

266]

[Illustration: FIG 33--CARTRIDGE-MAKING MACHINE FOR GELATINE EXPLOSIVES]

The issuing gelatine can of course be cut off at any length This is best done with a piece of hard wood planed down to a cutting edge, ie, wedge-shaped Mr Trench has devised a kind of brass fra fro its way along a series of grooves When the fraed to one end of the bottom frame, and fitted with a series of brass knives, is shut down, thereby cutting the gelatine up into lengths of about 4 inches

It is essential that the cartridgefor the screw shaft elatine One of these elatine into cartridges per diees ths of about 3 inches, the gelatine is rolled up in cartridge paper Waterproof paper is generally used The cartridges are then packed away in cardboard boxes, which are again packed in deal boxes lined with indiarubber, and screwed down air tight, brass screws or zinc or brass nails being used for the purpose These boxes are sent to the e or so should be removed and tested by the heat test, the liquefaction test, and the test for liability to exudation (Appendix, p 6, Explosives Act, 1875) A cartridge also should be stored in the azine in case of any subsequent dispute after the bulk of the material has left the factory

The object of the liquefaction test is to ensure that the gelatine shall be able to withstand a fairly high teht encounter in a shi+p's hold) without ether The test is carried out as follows:--A cylinder of the gelatine dynath equal to its diaes must be sharp This cylinder is to be placed on end on a flat surface (such as paper), and secured by a pin through the centre, and exposed for 144 consecutive hours to a te such tiht by es should relycerine upon the paper