based on the work of Commissions on which sat distinguished chemists of the day, and it became necessary to set up a State chemical department to assist in carrying this into effect.

For some time the science of chemistry had received a limited and vicarious assistance from State grants to the late Science and Art Department and to the universities, but it was reserved for the war to establish definitely and finally the position that the whole future existence of a State might and probably would depend on the existence of a flourishing and efficient chemical industry. This resulted in the definite steps of assisting the application of science to industry, and providing direct encouragement for workers in the purely academic field.

It is proposed, therefore, to sketch the development of the main chemical activities of the State, and to review the conditions in Great Britain in the hope that it may be of use generally to define the present position, and perhaps of interest to this Dominion in the present stage of its chemical development.

Defence.-Explosives.

It would appear that the importation of the technical process from abroad is no new thing, for it is stated that in 1314 gunpowder and guns were being imported into England from Ghent. Not only the material but the executant also appears to have been imported in the person of a John Crab, a Fleming, who took service with the English and supervised the guns and munitions used at Crécy. By 1338, cannon were mounted on board English ships of war, and in 1346 gunpowder was being supplied to the King. Although the manufacture of gunpowder is mainly a mechanical operation, variations in the composition which must have involved chemical experiment are recorded in such works as the 'Fire Work Books' of that interesting class, the Master Gunners. In England, a Master of the Ordnance in 1447 is stated to have made 20 tons of gunpowder. This manufacture, however, early became stabilised, and the proportions of the composition underwent little change until the middle of the nineteenth century, when it was modified, but as freedom from smoke began to be demanded a new propellent of a type that could be produced only by chemists was evolved.

It is of interest that Faraday was employed by the War Office as Lecturer at the Royal Military Academy from 1829 to 1853, and on appointment took as his assistant James Marsh, whose name, associated with the process for determining arsenic, is so well known to chemists. Marsh received the gold medal of the Society of Arts for this work, and a silver medal from the Board of Ordnance for his discovery of the quill percussion tube for cannon, and further he devised some of the earlier types of time-fuse. Abel succeeded Faraday at the Academy and began his long career of activity as scientific adviser to the War Office, becoming War Department Chemist in 1854.

It is necessary to mention some of the important advances made by Abel and his staff, including Kellner and Deering. By pulping guncotton, he rendered it safe to handle and store; his researches on the properties of guncotton laid the foundation of later work on its stability and explosive properties; and his research (with Noble) on the behaviour of gunpowder when fired is an example of a thorough investigation. Abel was consulted

also on subjects other than explosives, and in his laboratory were conducted experiments which led to the adoption in 1879 of the present close-test apparatus for testing the inflammability of oils, experiments on steels and the effect of foreign materials in them, experiments on dangerous dusts and on the cause of accidents in coal mines.

The work of Abel in rescuing nitrocellulose from the position of an erratic substance, liable to decompose and explode on storage, led to its use as a reliable explosive, not only for military purposes, but also in commercial compositions, such as sporting powders and blasting explosives.

When it became necessary to devise a smokeless propellent for the British Service, the chemical work was in the hands of Abel with his assistant Kellner, Dewar, and Dupré, and in 1890 this resulted in the recommendation for the adoption of cordite.

It now became necessary to extend the only chemical manufacture carried on at the Royal Gunpowder Factory, that of guncotton, by adding the manufacture of nitroglycerine, the technical handling of cordite, and plant for treating acids, and accordingly in 1891 a chemical manager of this section with a staff of chemists was appointed.

The chemical work carried out by the British Government for defence, both as to its immediate object and as to its reaction on the explosives industry of the country, is worth review. In such a review the position before the war may first be described. Propellent manufacture was seriously undertaken, the small quantity of high explosive used at this time being mostly obtained from private manufacturers. Guncotton, as has been stated, had been manufactured by Abel in a fairly stable form, and this explosive was chosen for the Service propellent cordite, together with nitroglycerine and mineral jelly, the mixture being gelatinised by acetone, so that in a plastic condition it might be squirted into the cords which give it its name. A close study was devoted to this manufacture in all its aspects; the processes of manufacture were greatly improved, and the dangers reduced.

The Royal Gunpowder Factory took its place as a model of an explosives factory, and afforded an example of what could be done by a State department in conducting a scientific manufacture with regard to improved technique, economy, and efficiency. Thus the method of nitration to produce guncotton was greatly improved in safety, freedom from fumes, and ultimate stability of the product, by the adoption of the process of downward displacement of the waste acids from the nitrated product by a layer of water; for nitroglycerine a displacement process by which the layer of that liquid, separating on the surface of the waste acids, was caused to overflow from the top of the vessel by introducing waste acid from a previous charge at the bottom, led to an increased safety and yield, and saved height in the erection of a factory; the chemistry of the process of guncotton boiling was worked out and placed on a scientific foundation; and acetone, which in the process of drying the cordite had been allowed to escape into the air, was recovered from the drying stoves and saved for further use. These advances in manufacturing method were taken up by other manufacturers, both in the United Kingdom and abroad.

In the technique of the manufacture of propellent explosives before the war this country then had advanced to a high pitch of efficiency, so

that when the demand came for enormously increased quantities of propellents, new factories, such as that of Gretna, took up the manufacture on lines already well established.

Safety in manufacture had also been closely studied, and precautions introduced that commended themselves to private firms. It may be said in this connection that the application of the Explosives Act of 1875 by the Home Office Inspectors of Explosives has been of much benefit to the explosives trade in reducing casualties. Perhaps in no other country are precautions taken to such an extent as in Great Britain, so that to visitors from abroad they sometimes appear unnecessary and vexatious, but experience has shown that the policy is sound, especially as it brings into all sections of the work an atmosphere of carefulness and responsibility, with an eventual gain in health of the workmen and freedom from accidents. Research on explosives before the war was carried out at the Royal Gunpowder Factory and at the Research Department, Woolwich. At the former establishment, the chemistry of the products manufactured was investigated, especially with regard to the mode of decomposition of guncotton, of nitroglycerine, and of cordite; their respective rates of decomposition at different temperatures were determined, a subject bearing on their behaviour on storage. Knowledge of this kind is essential in a Service such as ours, on account of the extremes of temperature from tropical to frigid to which explosives may be subjected in stations throughout the Empire.

At Woolwich an experimental establishment had been set up on the instigation of Lord Haldane to deal with explosives and metals used in gunnery. Here the study of the chemical and explosive properties of all types of explosives was undertaken and methods were developed for determining their stability and sensitiveness. This knowledge found application in laying down criteria for the choice of explosives for use in a Service whose demands are exigent on account of the drastic conditions above mentioned, affecting both storage and the design of mechanism containing explosives. So far as the subject-matter is not considered to be confidential, this work has been published in scientific journals, so that it is available in connection with the study of the theory of explosive substances.

A new phase was entered with the declaration of war, and ultimately all chemical help was mobilised for the defence of the realm. A nucleus existed at Woolwich, where the small staff of eleven chemists had been occupied in the study of explosives and their application. In two directions this experience proved of importance, for it enabled immediate answers to be given to questions which would otherwise have necessitated protracted storage trials, and it afforded the staff the training necessary to qualify them to meet the fresh demands that became urgent on the outbreak of hostilities.

After the beginning of the war the increase of work imperatively called for a larger staff, and more chemists were appointed, until at the beginning of 1917, the home supply being exhausted, permission was obtained to withdraw from France members of the Special Brigade, R.E., of whom more than thirty were transferred to the Department. Finally, the chemical staff numbered 107 chemists and physicists distributed in an organisation which had been gradually evolved, comprising sections for

dealing with different classes of work, such as organic chemistry, physical chemistry, analytical and general chemistry, physical investigation, calorimetry, stability, pyrotechny, applications of high explosives, fuse design, and records.

The manufacture of high explosives had not previously been undertaken by Government, and the known processes for making trinitrotoluene, which was early chosen as a Service high explosive, were unsatisfactory. One of the first subjects, therefore, taken up after the outbreak of war was the provision of an efficient and rapid process for the manufacture of trinitrotoluene, especially without the use of fuming sulphuric acid (oleum). From the results of a large series of nitrations in the laboratory, a process was evolved characterised by several novel features, and this was put to the proof on the semi-industrial scale of a quarter-ton, a plant being designed and erected in the Research Department, Woolwich, for nitration, including appropriate arrangements for the mixing and concentration of acids. This small plant substantiated in a remarkable way the process evolved from the laboratory work, and from the start turned out trinitrotoluene of good quality and yield. The process found immediate application in the large Government factories that were designed and erected by Mr. Quinan and also in numerous private works built at this time. The small-scale plant mentioned was used also for the purpose of training chemists, who proceeded to operate chemical plant in Government and private factories.

A study of trinitrotoluene in all its aspects was undertaken, and much attention devoted to its chemistry, the proportions in which the isomers occur in the crude product being determined by thermal analysis, and investigations were made on their interactions, stability, sensitiveness, heat values, and explosive properties. Most of the scientific results of this work have since been published.

When it became evident, as it soon did to Lord Moulton, that the supply of high explosives in use, lyddite and trinitrotoluene, would not suffice, the Research Department put forward mixtures of ammonium nitrate and trinitrotoluene, the amatols, as a result of a study of their properties and of their effects in shell-bursting trials. Gun trials confirmed these trials at rest, and the adoption of amatol as a high explosive quickly followed. Various methods of filling these mixtures into shell were at this time worked out, and many of them were applied on the very largest scale.

It was found that 80/20 amatol (80 parts of ammonium nitrate to 20 of trinitrotoluene) was less easy to bring to detonation than lyddite or trinitrotoluene itself, and it required special arrangements in the train of initiation of detonation. These were successfully devised, and good and trustworthy detonation of our shell was secured. Ultimately, amatol became practically the only explosive for land and aerial warfare, and justified the early estimate of its properties and capabilities. It is economical in that it makes use of a cheap ingredient, and has explosive properties that render it very suitable for the purposes for which it is used. In 1917 the production was at the rate of about 4,000 tons a week.

The Department continued the study of amatol, especially with regard to its chemical stability and compatibility with the various materials with which it came into contact. Certain impurities in ammonium nitrate were discovered to be objectionable, and investigation of these led to an

improvement in the purity of the ammonium nitrate supplied. The manufacture of amatol and the modes of filling it into shell occupied the attention of a large staff of chemists attached to the factories, and an increase in knowledge of its chemical and physical properties led to improved methods of handling it.

The Service propellent cordite required for gelatinisation in the course of its manufacture the solvent acetone, of which the supply ran short when the programme for propellents began to exceed all previous calculations. To meet this situation, cordite of the existing type was retained for Naval Service, but for Land Service a modification was introduced under the name of cordite R.D.B. (Research Department powder 'B'). This propellent could be made without any alteration in the plant required for the manufacture of cordite. Instead of acetone the solvent employed was ether-alcohol, and instead of guncotton a lower nitrate of cellulose was used. The great factory at Gretna, also built by Mr. Quinan, manufactured cordite R.D.B. exclusively, and this soon became the only propellent made in this country for the Land Service. It was produced both by Government and by private firms in enormous quantities. The alcohol was made in the country from grain, and ether was produced from it, so that dependence on sea-borne solvent was reduced. It was this need for alcohol that led to the restrictions imposed on that liquid when used as a beverage.

Numerous problems arose in connection with these manufactures as they developed and in the application of the explosives in the various types of ammunition, and these necessitated the study of the explosives in all their aspects. A large addition to the knowledge already existing was thus acquired on the more theoretical side of the study of explosives, and much of this has been made available by publication.

As the demand on our resources increased, and the necessity grew for investigating every source of supply and possible alternative, it came to pass that nearly every professor of chemistry in the country was mobilised for investigation in this field and in that of chemical warfare, and much valuable work was done by then, both of a research and inspectional

nature.

For the manufacture of explosives and the operation of filling them into munitions of various kinds in the existing factories and the new ones which sprang up, a large staff of chemists, amounting to about 1,000, was required, and in this way many chemists whose earlier work lay in quite other directions, such as at the universities or in teaching posts, received an insight into technology and took control of workmen.

During the war itself, instructional work in this subject was not wanting, for current progress in the factories under his control was discussed in a systematic manner by Mr. Quinan with representatives of his staff, a course which led to important improvements. Although most of these war-time plants for the manufacture of explosives have been dismantled, much of the technical experience gained has been saved, and will be found incorporated in a series of memoirs (Technical Records of Explosives Supply) published by H.M. Stationery Office. The information set forth in these volumes is in a form which has a much wider appeal than to the explosives technologist only, and their study is commended to those who take up the subject of chemical technology in any of its aspects.