not be done. Moreover, the attack on the rubber trees by fungoid pests is becoming so serious and the conditions of growth are so special, if not unnatural, that the future of the " natural " industry cannot be regarded as established and secure: it may well suffer the fate of the coffee plantations in Ceylon. The direct vulcanization of rubber, it may be mentioned, is now effected, in a most ingenious manner, by subjecting the material to the action of sulphuretted hydrogen and sulphur dioxide gases, the necessary sulphur being produced in situ by their interaction.
In the great dyestuff industry, the developments have been mainly in the direction of improvements in the manufacture of the intermediate materials and in the use of by products as substantive agents; the tendency has been to aim at the produc- tion of dyestuffs of ever -increasing fastness, that is to say, able to withstand light, soaping and the bleaching agents so largely used in cleansing fabrics. To cite an instance of progress in the making of materials, phthalic acid is now produced by merely passing the vapour of naphthalene mixed with air over a heated catalyst vanadium oxide instead of by the uncertain and troublesome method of heating with sulphuric acid and mercury. The most notable advance in the manufacture of dyestuffs is the use particularly of the hydrocarbon anthracene, the parent of the madder dyestuffs, in the production of a series of pigments known as vat dyestuffs; one of the latest of these is a green, in many ways superior to the green dyestuffs hitherto known. Like indigo, these are reduced, in the dyer's vat, to a soluble state, by means of sodium hydrosulphite; when the cloth has been impregnated with the solution and it is exposed to the air, the reduced material becomes oxidized and the dyestuff is deposited within the fibre. The really serious rival of indigo, in the future, may well be one of these dyestuffs, indanthrene, which is a magnificent blue considerably superior to indigo in fastness. The contention that natural dyestuffs are superior to the artificial is now disproved in a multitude of cases.
In addition to indigo, a variety of indigoid dyestuffs, similar in constitution to indigotin, including derivatives of this latter compound, are now in use, differing from it in shade of colour. Indigo, the product of various species of indigofera, has never been made artificially: only its chief pigmentary constituent, indigotin, is manufactured. Synthetic indigotin is now largely used, especially in calico printing; it is. of particular value in dyeing light, clear shades of blue. These cannot at present be secured with the aid of indigo; but the natural product is now known to be superior for heavy shades on wool (blue serge, etc.), owing to the presence of other dyestuff constituents, together with indigotin. Much has been done during the war to re- establish the indigo industry in India. If scientific findings be accepted, provided the commercial side of the problem be prop- erly handled, indigo may well resume the place it had lost as a dyestuff, though it can never attain to exclusiveness.
One important development in this field is to be chronicled. In photographic chemistry, which has long been at a standstill, there has been a notable advance, particularly in the all but complete control secured over the colour sensitiveness of the photographic plate. When the necessity arose, the required staining materials were produced in English laboratories with- out any difficulty and a command of the problems of staining has been secured far beyond that of the Germans.
Astonishment has been created by the discovery that cer- tain stains (notably pheno safranine) so diminish the sensi- tiveness of the gelatine-bromide emulsion to light, that if the most sensitive of plates be exposed, then placed during a brief period in a weak solution of the stain, development afterwards may be carried out in the weak light of an ordinary candle.
A great new field on the verge of development is that of the carbonization of coal at low temperatures, with the object of conserving the gaseous and oily products that are burnt waste- fully when it is used directly as a fuel, as well as of obtaining a solid fuel, of higher efficiency than coal, which can be burnt without producing smoke. The long-discredited process of making illuminating gas for domestic use by merely distilling coal must soon be superseded by rational methods, especially
as the demand for gaseous fuel is increasing very rapidly. The change will involve the disappearance of gasworks tar, so that the dyestuff industry will be forced to rely upon the high tem- perature coking ovens for its raw materials or discover other sources of supply; the use of tar on roads will also be diminished. The development of a synthetic process to convert a mixture of carbonic oxide and hydrogen into methane may well prove to be of importance in this connexion. It is known that the conversion may be effected without special difficulty, using nickel as a catalyst ; but the process has yet to be developed on an economic scale. The successful use of nickel as a catalyst, in purifying coal gas from sulphur (other than as sulphuretted hydrogen), may be referred to as another striking instance of industrial advance.
A wave of scientific method is pulsating throughout the world, which is everywhere influencing industrial development. There is an obvious desire to assimilate the procedure of the works with that of the scientific laboratory and particularly to develop the use of machinery in the former; but if empiricism be departing, progress is at very different rates, not only in different lands but in different industries, some being very slow to move. The chemist of the future, to carry the burdens of his day and succeed, will needs be both very widely trained and gifted with reflective power and insight: victory must fall to the scien- tific rather than to the strong or the swift.
Progress in Organic Chemistry. It is necessary to be clear what the expression " Organic Chemistry " should cover. As a philosophy, at the present time, chemistry is in a difficult position owing to the extent of the field, the over-subdivision of the sub- jects and the ever-growing tendency of workers to specialize, knowledge of facts having been unduly cultivated at the expense of breadth and precision of scientific outlook. Liebig remarks, in one of the earliest of his celebrated Letters on Chemistry, " The attaching too high a value to the mere facts is often a sign of a want of ideas. It is not fertility, but poverty of ideas which clothes itself with a mass of coverings of all sorts or wears old, battered, threadbare and ill-fitting garments." It is to be feared the criticism holds to-day.
The science of chemistry is conventionally divided into two- main sections the inorganic and the organic; but these are most unfortunately defined. Substances derived from animals or plants formed it was thought under the influence of a vital force were originally the subject matter of organic chemistry. When the discovery was made that such substances could be prepared by artificial means first in 1828, when Wohler synthe- sized urea organic chemistry became the study of the com- pounds of carbon: though the systematic definition was a gain of precision, the chemist's outlook was narrowed and confined, as attention was withdrawn from the concurrent study of vital phenomena. A more unfortunate consequence of the rigid sub- division of the field is, that the two branches have been treated as separate disciplines; usually the carbon compounds have been regarded as the subject mainly of higher academic and profes- sional study, so that those who have sought to acquire only an elementary understanding of chemistry have been denied the very knowledge likely to be of most importance to them.
The study of carbon compounds has been prosecuted with extraordinary diligence, during the past 5 years, by a large number of workers who have been attracted by the beauty of the problems the subject affords and the consistency of its methods. An astounding fabric of structure has been reared which is all but unknown, except to the few; and yet it is laid upon the simplest of foundations and its main features and lessons are easily grasped. No one can claim to be a chemist who is not seized with the spirit of this knowledge.
The study of structure has played little if any part in inorganic chemistry and until recently this branch attracted relatively few workers; it has further suffered, not only from neglect to apply the lessons to be derived from carbon compounds but owing to its own subdivisions through the treatment of metals under metallurgy, as a separate subject. Of late years subdi- vision has been carried still further, by the creation of a physical section of very limited range, as something apart ; the attempt has
