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of this head against shields was very satisfactory; moreover, the bursting of the head considerably aided the ranging. In percussion fire the effect was not equal to that of a modern high-explosive shell, but greatly surpassed that of ordinary shrapnel. The manufacture was only slightly more troublesome than that of other shrapnel, and the shell effect of the head and the assistance it gave to ranging more than compensated for this, so that, on the whole, the shell was con- sidered satisfactory. Universal shell, in any case, was no substitute for H.E. shell, and as time went on and the use of shrapnel became more and more limited to particular episodes of fighting, universal shell, like ordinary shrapnel, diminished in importance. In practice, however, in both armies and especially in the Austro-Hungarian, a large proportion of the ammunition had still to be in the form of either shrapnel or universal shell, owing to the lack of material, and particularly of explosives. And the practice of packing explosive be- tween the bullets of the universal shell had to be abandoned.

Iron Bullets, The want of lead caused a substantial falling-off in shrapnel production. In 1916 the manufacture of iron shrapnel bullets had already begun, and from 1917 onwards leaden bullets practically ceased to be made. The bullets were cast or pressed. The former displayed undesirable ridges and corners; the latter were more difficult to produce in large quantities. Another disadvantage was that not only did the lesser specific gravity of the iron bullets in relation to that of the lead-antimony bullets result in a lesser power of penetration, but a much smaller number of the former could be got into a shell than of the latter, which, being smaller and fitting closer together, permitted full utilization of the space. It followed from this that the total weight of the shell was less, so that shooting with the existing sight-graduations became complicated and produced different results. The packing in with explosive, in the Austro- Hungarian universal shell, became impossible with iron bullets, because of the danger of prematures.

Coloured Smoke-clouds. The effort to render the smoke of ex- ploding shrapnel more visible, even over snow-fields, led, in Austria- Hungary, to the use of a red colouring matter (oxyhydrate of iron), which made the smoke-burst half red. This colouring also facilitated the keeping of a due distance between the shots. I n Germany various devices were employed for colouring the smoke of certain shells.

Fuzes and Ignition. The fuzes ordinarily used by both armies in time shrapnel fire were T and P fuzes of the setting ring class. They were used both for shrapnel and for time fire with nose-fuzed H.E. shell. After the abandonment of H.E. time fire (which was dictated by the necessity of simplifying the mass-production of one of the fuze parts) a simple explosive shell fuze was adopted.

The Austro-Hungarian artillery employed base-fuzes much more than the German. That most in use was one of Krupp manufacture which had an effective ball-safety. The design of Austrian base- fuzes differed considerably from that of German as regards the transmission of ignition. Base-fuzes proved quite as satisfactory as nose-fuzes in the war. Explosions in the bore were no longer caused by fuzes, as they appear to have been in peace-time.

Soon after the war opinion changed regarding the relative merits of shrapnel and explosive shell. The estimate of the value of the explosive shells in percussion and time fire likewise varied from time to time according to the nature of the ground being fought over. While H.E. effect was almost entirely lost in the soft soil of Galicia and Poland, on rocky ground (and more especially on the Carso) the effect of this kind of fire was intensified by the splinter effect of the stones and, moreover, blinds seldom occurred. Efforts were directed towards the production of a sensitive instantaneous fuze, especially in the western and eastern theatres of war, where also time explosive fire was more in demand than in the Italian theatre.

Germany's sensitive instantaneous fuze, produced in 1916 and 1917 (see AMMUNITION), was of an extremely simple pattern and safe in the bore. It was not very satisfactory, however, for flat angles of de- scent, being apt to go blind in such cases. By the end of the war Austria-Hungary had also produced a sensitive fuze, constructed on similar principles and exhibiting similar defects. These fuzes were, of course, necessarily nose-fuzes. A device for bringing into the system a long or short delay element, or both, can easily be added ; but the question of the instantaneous fuze is still open.

In the western theatre flat-trajectory ricochet fire with long alloy fuzes was very successful on suitable ground. It served as a sub- stitute for H.E. time fire, and was indeed more effective when the burst occurred at the proper height. However, it depended on the coincidence of several favourable conditions. Experiments were made with mechanical time-fuses, especially for use with anti-aircraft guns, in order that the igniting composition of the time fuzes should not be affected by atmospheric conditions. The best results seem to have been obtained with those made by the watchmaking firm of Junghaus, which brought out designs both in Germany and Austria-Hungary. The Krupp model was driven by spring power ; the Junghaus by a centrifugal device. The success of these designs was not in proportion to the costliness and difficulty of manufacture. These fuzes were but slightly superior to the time-composition fuzes, and on the other hand introduced new sources of error. Moreover, their manufacture depended on the existence of a large-scale clock industry capable of mass production.

Substitute Metals. The lack of brass, of which fuzes were nearly always made, necessitated the use of substitute metals for this

purpose. The best results were obtained, for a number of the fuze parts, with an alloy of zinc and aluminium. Iron was also satisfac- tory for fuze bodies and other portions. Only certain especially delicate interior parts (such as safety-ferrules) were made of brass as before. Both Central Powers soon became very successful in the employment of other metals for fuzes, so that the use of these sub- stitutes might well be continued without disadvantage even in peace-time, when normal supplies of raw material are available.

Explosive Charges and Their Filling. Before the war trotyl (T.N.T.) had been completely adopted for shell fillings in both Germany and Austria-Hungary. This was inferior to ekrasit (picric acid) in explosive power, but its greater insensitiveness to shock, and also the fact that its preparation was both easier and less injurious to health, gave it a considerable advantage.

While Germany, owing to the high development of her chemical industry, already had, in peace-time, several establishments for the manufacture of trotyl, Austria-Hungary was dependent on Germany for this substance at the outbreak of the war. A few months later she began to make her own trotyl, and Germany set up a number of additional factories; nevertheless, the supply was soon outdistanced by the enormous demand, owing, once more, to the scarcity of raw material. Not only had recourse to be had to picric acid (known in Austria-Hungary as ekrasit), but a number of other explosives had to be produced from the available raw materials and used as artillery fillings. Some of these were difficult to work, some not over-safe, some inferior in effect. The demand continued to increase, for with the ever-growing multiplication of new fighting devices, such as trench mortars, grenades, air bombs, etc., the use of explosives was being continually extended.

In Germany the satisfaction of the immense demand was less diffi- cult than in Austria-Hungary, where the army administration was dependent for its explosives upon two public and two privately owned factories. At the beginning of the war, with the exception of one privately owned ekrasit plant and one ammonal works, there were no factories for ammunition explosives in the country.

Trotyl was almost invariably poured directly into the shell cavity. To prevent crystallization the stuff was filled under pressure, and constantly stirred till solid. The exploded cavity was made by boring. The projectiles filled by this method proved highly satisfactory, and it was used up to the end of the war for all shells subjected to high stresses, as far as the supply of trotyl permitted. Complaints were made only against " crude trotyl," which contained insufficiently nitrated portions and was apt to " exude."

The manufacture of picric acid necessitated great precautions because of high melting-point, and was also very inconvenient by reason of the injurious nature of the fumes and dust. Hence ekrasit was not poured into the shell in a molten state like trotyl, but after the addition of a " phlegmatizer " (e.g. mononitronaphthalin) was filled in in large masses and pressed down with wooden stemming rods. Later on, in order to simplify the process, it was made into compressed blocks, and these were fixed into the shell with paraffin and resin. For the larger calibres a combined picric and cast-trotyl filling was used. Picric acid was thus restored to its earlier importance in shell-filling, and, in spite of less strictness in inspection conditions, proved as satisfactory as trotyl up to the end of the war.

The immensity of the demand soon made new expedients neces- sary. In Germany, dinitrobenzol was used to some extent. It an- swered well when a more vigorous substance was used with it to start detonation (trotyl blocks). Its troublesome idiosyncrasies in working were considerably lessened by the use of suction apparatus. Trini- tro-anisol, more powerful than trotyl, but also more easily exploded, was also used in Germany. Because of its unpleasant physiological effects, it was, however, employed only for the projectiles of trench mortars and trench munitions, and for naval mines.

The most important of the measures taken purely for economy was the use of ammonium-nitrate explosives. These are made by mixing finely powdered ammonium nitrate into the molten mass of a nitrated substance. Hence the explosives of this class actually used ' were based on trotyl or dinitrobenzol in Germany and trotyl only in Austria-Hungary. By this method explosives very little inferior to trotyl could be obtained and the total production considerably increased. Although the sensitiveness to shock was found to be rather greater, the manufacture was almost as convenient as that of trotyl. Picric acid could not be treated in this way.

In Austria-Hungary there arose a very extensive demand for toluol-ammonal, which consisted of ammonal with from 10 to 30 per cent addition of trotyl. The composition was first compressed into blocks, which were inserted into the projectile in cardboard tubes. Solid-filling by means of molten paraffin or trotyl poured into the interstices between those tubes did not prove satisfactory in the Austro-Hungarian base-fuzed shells, as set-backs occurred on dis- charge. For this reason the compressed blocks were inserted without the cardboard tubes, and were made to adhere to the shell-wall with a composition of lime, resin, and paraffin, or by means of cast trotyl. The best results were finally obtained by the use of pitch. Hot pitch, in the form of dust, was sprayed onto the shell walls (Fritzsch's process). In the case of a few large calibres trotyl was filled onto a short block of compressed T. ammonal secured by cast trotyl.

1 Called amatols in Great Britain.