through a side tap. In a later process the nitroglycerine is allowed to separate in the tank in which it is made, and waste acid is made to enter the bottom of the vessel, gradually raising the level of the contents till the floating nitroglycerine flows out by a pipe at the top. This arrangement dispenses with stop-cocks, the friction of which introduces an element of danger. The nitroglycerine is then washed repeatedly with soda solution to remove any traces of acid and with water only to remove the alkali, and is finally filtered.

Gun-cotton, the second component of cordite, is also made by the aid of a mixture of the strongest nitric and sulphuric acids acting on cotton waste. Chemically it is usually described as trinitrocellulose, and accordingly it may be made from anything containing cellulose But the point to be remembered in connexion with the agitation which ended in cotton waste and yarn being declared contraband in August 1915 is that, though many materials have been tried, none has been found to be so satisfactory as the waste, or to yield quite the same quality of trinitrocellulose. For instance, cotton that has been strongly bleached or mercerized takes up less nitrogen and is more difficult to render stable. It follows that gun-cotton made. from substitutes such as wood must at least be different from, and almost certainly inferior to, that made from cotton waste, and that powder containing it must give different results when

used in a gun, all the calculations for which are based on the assumption that the product from cotton waste is to be employed.

In the process of manufacture the cotton waste is picked over to remove impurities, teased in a machine and dried in hot air. For the actual nitration there are several processes. In that devised by Abel a charge of 1 lb. is immersed in the acids for five or six minutes and then after being squeezed is placed in an earthenware pot, where it remains for twentyfour hours while the nitration is completed. When the cotton is taken out it is put into centrifugal machines which remove much of the acid, and is subsequently washed in abundance of fresh water. In another process developed in Germany it is charged into perforated iron baskets which are rotated in the acid bath by a centrifugal machine. In a still newer arrangement it is pushed below the surface of the acids contained in a large earthenware pan, and a layer of water is run in over them; when nitration is finished the acids are allowed to run out slowly while an equal quantity of water is distributed over their surface, ultimately running through the gun-cotton, which is left containing only a little acid. It has next to be freed from various impurities which if not removed would render it unstable, and for this purpose it undergoes a number of successive boilings extending over many hours. Pulping follows, carried out in water that is constantly

renewed, by a beating engine which breaks down the fibres of the cotton, so that grit and other impurities are set free. The pulp is next washed several times in large tanks or "poachers," continually agitated by a paddlewheel, in which also different batches are mixed to secure uniformity of product. After being fished out of the poachers the pulp is lightly compressed into cylinders three inches in diameter, in which form it is employed for making cordite; but if it is wanted for use in mines or torpedoes it is moulded into slabs under hydraulic pressure of 5 or 6 tons to the square inch. Such slabs of wet gun-cotton can be sawn or turned in a lathe, and are not inflammable, so that they can be stored with safety, yet they can be detonated with the aid of a primer of dry gun-cotton. The hole to receive the mercury fulminate detonating tube which is necessary for this purpose is bored in the primer before it is dried.

The fibrous structure of cotton is not sufficiently destroyed in the ordinary process of making gun-cotton to permit the latter to be used as a propellant, and no matter how strongly it is compressed the minute tubes of the fibres convey the igniting flame into the interior of the mass and cause extremely rapid combustion of the whole charge, the result being, not the progressive burning required,

but an almost instantaneous production of great volumes of gas which strain the gun without giving much velocity to the projectile. No success in utilizing gun-cotton as a propellant was therefore obtained until it was found that the original structure of the cotton can be destroyed by gelatinizing the gun-cotton with the aid of a solvent, so that it burns regularly from the surface. It is on this principle that the nitro-cotton powders used by Germany and other countries are made. They are composed either of true gun-cotton (trinitrocellulose) or of collodion cotton (dinitrocellulose), which is less highly nitrated, or of a mixture of the two varieties.

We now come to two substances used solely as high explosives-picric acid and the still nore notorious trinitrotoluene, variously known as trotyl, trinol, tolite, trilit, and T.N.A. Both are obtained ultimately from coal. The former, trinitrophenol, is made by the nitration of carbolic acid, a product of the fractional distillation of coal tar; the latter by the nitration of toluene, a hydrocarbon contained in the crude benzol also distilled from coal tar and washed out from coal gas. Picric acid is the older of the two. It was introduced into the French service as a high explosive for shells in 1886 by Turpin, whose melinite, so called from its honey-like colour, was in its final form simply the fused acid. When the news of Turpin's shells reached this country the nature of the substance was soon realized, and after experiments at Lydd it was introduced into the British service as lyddite, poured directly into the shells in a molten condition. It can be made and transported without danger, is very stable, insensitive to percussion, and not liable to be exploded by the shock of discharge of large guns. It is extremely powerful with thorough detonation, but for that a very strong detonator is required. One of its drawbacks is that its melting point is rather high, and another is that in contact with metals it forms salts which in some cases are very sensitive to heat, percussion and friction; for this reason the interiors of shells filled with it are coated with varnish, and in the course of manufacture it is carefully kept from contact with metallic surfaces.

T.N.T., on the other hand, has a low melting point, does not attack metals, and is very stable. It is poured into shells in the molten state like picric acid, but is not quite so powerful. The practice of compressing it in the shells has given rise to serious accidents in

It may have been noticed that the chemical names of the explosives which have been described all contain the word "nitro," showing that nitrogen is a constituent of each, although it is not to be found in the original materials— glycerine, cotton, carbolic acid and toluenefrom which they are made. Now nitrogen accounts for roughly four-fifths of the air we breathe, and is therefore an extremely abundant substance; but unfortunately the chemist cannot make much use of it in the form in which it exists in the atmosphere, because it is so inert as to refuse to take part in his operations. But it is more accommodating when it is already "fixed" or combined with some other element, and the combination which is generally best suited to his needs as regards the manufacture of explosives is nitric acid, one of its compounds with oxygen. Nitric acid is therefore of great importance, indeed is essential, for the production of explosives, and it is interesting to enquire from what source Germany and other countries obtain their supplies.

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The great bulk of the nitric acid used in the industries of the world is made from the caliche containing Chile saltpetre (nitrate of soda), of which there are immense deposits along the coasts of Chile and Peru, and of the total exports of nitrate Germany before the war took more than any other country, her proportion being about one-third, or more than 800,000 tons annually. From it she made about 100,000 tons of nitric acid, though some was used among other purposes for converting the potassium chloride of her Stassfurt salt deposits into ordinary saltpetre (potassium nitrate), required in the manufacture of black gunpowder. When her mercantile marine was swept from the seas, her supplies of nitrate were presumably cut off, and the question presents itself how she managed to get the nitric acid necessary for making her explosives.

Apart from accumulated stores, there were two sources of supply open to her. Towards the end of the eighteenth century the great English natural philosopher Henry Cavendish

discovered that the nitrogen of the air could be made to combine with oxygen under the influence of the electric spark, and about 120 years later this method of producing nitric acid and nitrates became practical. Cheap electricity being essential for commercial success, the manufacture was established in Norway, where water-power is abundant, and German capital took a large part in its development. It has been calculated that if all the power available in Scandinavia, with a smaller amount

in other parts of Europe, were utilized in making nitrate from the air, some fifty million tons could be produced every year, though before the war the annual production was far below 200,000 tons. But Germany had still another string to her bow, and the fact that the Badische Aniline Company, one of her most important chemical manufacturing concerns, withdrew all the capital it had sunk in the Norwegian industry suggests that she thought it a better one. Ammonia, a compound of nitrogen and hydrogen, is obtainable in abundance from a number of sources, as from the distillation of peat (of which there are enormous deposits in Prussia), from the coal used in blast furnaces and in making metallurgical coke and coal gas, and from the direct combination of atmospheric nitrogen with hydrogen by the aid of electricity, and when obtained it can be oxidized to nitric acid by a process worked out by the German chemist Ostwald. In this way one German colliery alone made as a by-product some 2,000 tons of nitric acid in 1912, besides other nitrate, and there is little doubt that after that date works were erected in Germany for carrying out the process on a much larger scale.

In conclusion a reference may be made to asphyxiating gases, which, although not ammunition in the ordinary sense, were used to produce the same effects as ammunition in killing or disabling men. Heralding their resort to this breach of the recognized rules of war by wholly false accusations that such gases had been used by the Allies, the Germans first adopted them towards the end of April 1915 in an attack on a portion of the Allied front held by the French to the north-east of the Ypres salient. Although various substances appear to have been employed, the chief was probably chlorine, a heavy greenish-yellow gas, which physically fulfils the

conditions required for the purpose and is capable of producing the asphyxiation (spasm of the glottis) and subsequent bronchitis which were the symptoms observed. The preparation of this gas, which can readily be reduced to the liquid form by moderate pressure at ordinary temperatures, was a large industry in Germany before the war. Much of it was exported to other countries, and, as this trade was cut off, the manufacturers, among whom the abovementioned Badische Aniline Company was prominent, had an abundant surplus of it to spare for murdering purposes, and also possessed ample supplies of tanks and vessels for its transportation. Receptacles filled with the liquid being brought up to the trenches, it could be squirted from hose by its own pressure in the required direction, resuming its gaseous form when relieved from that pressure. Equipments were also employed designed to be carried on the back of a man, who was supplied with oxygen-breathing apparatus so that he himself was unaffected by the gas. Poisonous and "lachrimatory" gases were also sometimes fired in large shells.

The Allies took successful measures to combat the effects of the gases by providing their men with masks and respirators, and on May 18 Lord Kitchener in the House of Lords foreshadowed the use of gas by the Allied forces to remove the enormous and unjustifiable disadvantage" which must exist for them if nothing were done to meet the enemy with his own methods. Accordingly gas was employed by the Allies for the first time towards the end of September 1915. As was to be expected of them, the Germans complained, with characteristic lack of humour, that their loss of ground was due "not to any soldierly qualities of the English, but to a successful surprise by gas attack."

TAMES PA

Ο 3

N April 25, 1915, the mighty Battle of the Landing was fought at the Dardanelles. Under cover of darkness, and under the protection of the Fleet, a great army was conveyed towards the rocky and desolate shores of the Gallipoli Peninsula. In the dim light of dawn landings were made at half a dozen points, and by nightfall the exploit which the Turks and their German mentors had deemed impossible was actually accomplished. The army was ashore, and by desperate valour had made good its position. Its foothold was scanty, its peril still seemed great, its losses had been heavy; but it had landed, and the heroism of its assault had added fresh glories to the military annals of the British Empire. The amazing gallantry of the troops rang throughout the world, and for a time eclipsed all thought of the possible ultimate dangers and difficulties of the enterprise. It seemed to those watching from afar that further and complete success could not be denied to the men who had dared and done so much already. Throughout all the subsequent tragic episodes of the Dardanelles campaign the glowing triumph of the Battle of the Landing still shone with a light which was never dimmed. The memory of its glory remained a powerful influence when months afterwards men began Vol. V.-Part 61

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to ask whether the attack upon the Dardanelles could ever be carried to a successful conclusion. No one cared even to suggest that the dogged bravery of the immortal 29th Division, and the undaunted devotion of the indomitable Australian and New Zealand Corps, might have been in vain. But their sacrifices were never made in vain. The good Australian and New Zealand blood shed at Gallipoli sealed and glorified for ever the patriotism of the Commonwealth and the Dominion, just as surely as if the impetuous heroes had died on Sydney Heads or on the shores of the Hauraki Gulf. At the gateway to Constantinople the men of the younger nations were fighting for the safety of their own fair lands, and from their graves sprang imperishable ideals which inspired their sorrowing kinsmen with renewed determination. Upon Englishmen the stubborn resistance encountered at the Dardanelles had a like effect, for it deepened the national resolve to pursue the war unflinchingly until Germany and her subordinate Allies were overthrown.

The Battle of the Landing was in certain respects unlike any other battle of modern times, by reason of the peculiar disabilities imposed upon the soldier who directed it, General Sir Ian Hamilton. He was in an extraordinary position. He had not planned the