methyl-anilin, known as "tetryl," is used as a primer or detonator.

Both picric acid and T.N.T. will burn quietly in the open, if ignited.

How, then, are they and other similar materials brought to explosion? In some cases by actual ignition. For example, the heavy charges of smokeless powder in the guns are usually ignited by means of a small charge of gunpowder placed in the chamber with the propellant, and this, in turn, is ignited by a detonator, which, as a rule, is a substance which is caused to decompose by shock. The so-called fulminate of mercury such as is used in ordinary cartridges, and exploded by the blow from the hammer of the weapon, is a material of this sort. When struck it explodes, either from the vibration of the blow or from heat generated by the blow. The explosion of the fulminate starts certain vibrations in the air or ether, and these seem to be of such a charactes as to be taken up by the molecules of the explosives, with the result that these, in turn, become disrupted. It is, in principle, like what occurs if a bow is drawn across the string of a violin in front of a piano when the loud pedal is pressed down. The single string of the piano which corresponds to the tone of the violin in its length of vibration will respond. It is also similar in principle to wireless telegraphy, save that in both these latter cases no decomposition of material ensues, while in the case of the explosive the molecules are shattered by the vibrations from the explosion of the fulminate.

The explosives all give out heat when they decompose, and heat, in turn, always hastens any chemical change. Hence, any decomposition caused by the vibrations of the detonator is at once propagated through the

mass.

In the incendiary bombs, which are recently so much in evidence, they have found phosphorus, inflammable liquids of various sorts, and a mixture known and used in the arts, and called thermite. It consists of a mixture of

oxide of iron and powdered aluminium. When ignited by a primer just before the bomb bursts, it generates an intense heat, and molten iron is scattered in all directions. This iron is, indeed, far above its melting point, attaining temperatures as high as 3000° C. Its incendiary capabilities are sufficiently evident. It is stated that phos; phorus has also been incorporated in shrapnel and grenades. It aggravates the wounds produced, since the tissues burned by the phosphorus are only very slowly restored. It is also true that the phosphorus, which takes fire on exposure to the air, leaves a cloud of white smoke locating the fall of the shell. They have been called the by day and a flash of fire by night, which again aids in "woolly bears."

Of the raw materials demanded for these explosives, outside of nitrogen, we are fortunate with respect to cotton, iron, fuels, and metals, although there is an enormous demand for cotton. An adequate supply of glycerin calls for foresight. It is a by-product of the soap industry, and can be obtained from animal fats, and from some vegetable oils by other processes, but the ordinary sources of supply would probably have to be augmented to meet war requirements.

The poisonous gases employed in the present war appear to be chlorine, or mixtures of chlorine and some bromine. Both act violently upon the mucous lining of the throat and lungs, 2 per cent by volume of chlorine often proving fatal. Bromine is, if anything, even more poisonous than chlorine. It is a liquid at ordinary temperatures, and is supposed to be used in shells, since the liquid is scattered as such, and on evaporating does its cruel work. According to accounts, liquid chlorine, or more probably chlorine gas, has been forced through pipes in front of the trenches, and carried by the wind against the enemy. Only a heavy gas could be thus used. If chlorine is a fair weapon, we have a plentiful source of it in our salt deposits,

Liquid Fuel.

81

Both aircraft and undersea boats, in their remarkable development, have presented new problems which must be duly considered in a preparedness programme. From a chemical standpoint the most urgent of these are adequate supplies of liquid fuels, and the devising of metallurgical products which shall combine maximum strength with minimum weight. Much advance has been made in the production of alloys of aluminium and magnesium, the two available metals with the least specific gravity.

The liquid fuel problem is upon its face one of some seriousness. In this country gasoline may be said to be almost the only liquid fuel in use to drive the internal combustion engines. The use of these engines has increased with enormous rapidity, not only as motive power for vehicles and boats, but as stationary engines, and in the form of portable engines for farm use, concrete mixers, and the like. In the war area such motors are attached to almost every movable object from aircraft to ambulances, and even to field and siege guns. The heavy petroleum oils, from which the gasoline has been removed, are also used as fuels on some of our battleships, on some of the western railroads, and for boiler plants in localities in which such oil is readily obtainable at low cost.

Gasoline is not a chemical entity. It is a name for a mixture of volatile substances obtained by distillation from the crude natural petroleums. The supply of natural gasoline must ultimately depend upon the supply of these crude oils. Before the advent of the gas-motor, the oil refiners were at a loss to find a market for these volatile oils. The burning oils, kerosenes, were made to carry as much gasoline as the rigid legal requirements regarding fire-tests would permit. To-day the situation is reversed, and the gasoline at present on the market carries as much kerosene as the traffic will bear, that is, as much as can be used and still retain sufficient volatility to enable the cylinders of the engine in adequate quantity. Both carvapour to pass with air from the earburettor to the burettors and engines have been modified to meet this the demand for such fuel actually outstripping the supply necessary change in the character of the fuel supply. Is gasoline would seem to indicate this, but an analysis of even upon a peace footing? The rapid rise in the price of the situation leaves the matter somewhat in doubt, at least is dealt with in detail in a communication dated February 2, so far as the immediate future is concerned. The question 1916, sent to the U.S. Senate at its request by the Secre 266 million; that of the world in 1900 was 149 million. tary of the Interior. The total production of crude oil in the United States in 1900 was 63 million barrels, in 1915 In 1915 it had risen to 400 million. The consumption of gasoline in the United States in 1899 was about 7 million barrels, in 1915 it was 41 million. The ratio of increse of production of crude oil is about 1:4; the gasoline consumption 16. This result has been made possible by improved refinery methods, and by alterations in the character of the burning fluid known as gasoline, as just described.

In his response to the Senate inquiry as to the cause of the sudden rise in the retail price of gasoline, the Secretary names six contributing factors: (1) Increased consumption of gasoline, which was 25 per cent greater in 1915 than in 1914; (2) Increased exports (about 1 million barrels in 1915); (3) Depletion of stocks of gasoline held in January, 1915. There is almost none so held to-day; (4) Decrease in the production of crude petroleums yielding the larger percentages of natural gasolines. In the "Cushing field " alone, the wells were, some months ago, yielding less petroleum than in April, 1915, by an amount equal to 50,000 barrels of gasoline a day; (5) Increase in price of crude petroleum, which has been advanced from 1.45 dols. per barrel on January 1, 1915, to 2.25 dols. per barrel on January 1, 1916. Gasoline has advanced from 12 cents to 21 cents (wholesale) in the same interval. If

this advance in the price of the crude oil bears any relation to the ultimate natural supply, it must apparently be anticipatory to a large degree. The price of gasoline has advanced more than proportionately, but this may be partially accounted for by temporary inability of refiners to handle the necessary volume of crude material; (6) the last factor is what the Secretary calls "Financial influences," and under this caption he discusses the fluctuations of the stock quotations, and concludes that in the case of the larger and stronger companies the price which the consumer pays does not depend alone upon the cost of crude material.

Apparently, then, the current price of gasoline is not an accurate measure of the imminence of a dearth of liquid motor fuel.

Other figures of interest are also to be found in this letter. Experts have estimated that, taking into account the known possibilities, the various so-called "fields" of petroleum have been exhausted to amounts varying from 8 to 93 per cent. But they also estimate that these fields may yet be counted upon to yield something like seven billion six hundred million barrels of crude petroleum. There is no accurate factor by which to translate this into gasoline because of changing practices; perhaps it may represent two billion barrels. These figures also take no account of the oil-shales known to exist. These are rocks more or less saturated with petroleum. The total possible yield from shales of the same character as are now worked in Scotland might furnish further billions of gallons of crude petroleum.

So much for the natural gasolines. But our resources are by no means exhausted with them, although the situation demands careful and intelligent study, if we are to be in a position to meet emergency demands.

In the first place, we have means by which we can produce what may be called artificial gasolines. We are already condensing to a liquid, the natural gases which are associated with the petroleum deposits and mixing this very volatile material with kerosene, the mixture constituting an artificial fuel.

It has, moreover, been found that there are several ways in which the less volatile components of petroleum can be decomposed into substances which are readily volatile, and at least two commercial processes are now in operation to effect this conversion of heavy liquids into what is, in effect, a gasoline. These volatile substances are, in turn, used directly, or are mixed with some kerosene to make a burning fluid of acceptable quality. In this way the proportion of available material for gas motors is much increased. It will be some time before such operations can be conducted on a 50,000-barrel-a-day scale, and we may probably expect to see the price of such fuel continue to advance in the immediate future if the principle of supply and demand is the controlling factor.

But gasolines are not the only type of liquid fuel which it is possible to use in motors. In Europe, benzol, a coaltar product, has long been used, and it is reported that Germany is using at the present time a mixture of equal volumes of alcohol and benzol with much success. The production of benzol is essentially controlled by the market for coke. Alcohol can be produced in great quantities from potatoes, and also from sawdust and woodwaste. Both benzol and alcohol have the disadvantage that they are less volatile than gasoline, and require a "starter" of gasoline, but, with modifications of our present devices, particularly with respect to electric heaters, their use is practicable. In Germany they are said to be using gasoline to start the motor.

Obviously, the gas engine has proved its claim to permanence, and the importance of this form of motive power in peace or war can hardly be overestimated. If we have plenty of time to prepare, the liquid fuel problem may not be serious. In an emergency, it behoves our Government to be ready to meet an acute demand.

The lighter-than-air craft has not apparently appealed

to the Allies. If we should determine to add zeppelins to our outfit, hydrogen is to be had in plenty, by the electrolytic decomposition of water for initial inflation. To supply the constant loss through the envelope, an apparatus similar in principle to the acetylene generators formerly used on automobiles is now used, in which water can be dropped on a solid mixture such as silicon and caustic soda. Hydrogen gas is thus generated, and can be introduced into the envelope to compensate for losses. This apparatus is either carried on the dirigible or transported by automobile as needed.

Prognosis and Research.

These are but a few of the material demands which would confront us if our preparedness is ever to be tested. But back of these and vastly more important than any one of them is the need for something like an adequate notion on the part of our Government, and our industrial leaders who must actually supply our material needs of what research and scientific method stands for and can accomplish. However we may criticise Germany, we cannot avoid a tribute of respect to the thoroughness with which she not only anticipated the events and material conditions of the war, but has met the rapidly changing conditions with fresh and more efficient weapons and munitions. It is impossible to think of Germany as entering a war as we are said to have entered the Spanish war, with black powder, when all other nations, even Spain, were using smokeless powder. Nor can we think of Germany, or perhaps any other of the nations, with our resources and self-assumed responsibilities to our neighbours, continuing with but one single small plant (in North Carolina) equipped to fix the nitrogen from the atmosphere, without which it is hardly too much to say that we might be brought immediately to our knees in the event that the South American supply of nitrate was suddenly stopped by our enemies.

The well-worn expression "in times of peace prepare for war" can nowhere be better applied than in the encouragement of research. Our army and navy departments are not like our industrial concerns. The latter can afford to temporise and take chances on producing a profit from the use of antiquated machinery or methods. In the contest of war there is no quarter for weapon or craft that was the finest yesterday, and no time to wonder how the enemy manages to keep one lap ahead of us.

There is much evidence to show, in chemistry at least, that we can at least hold our own in the embodiment of chemical principles and laboratory processes in profitproducing large-scale plants, but we do need to culti vate a greater appreciation for the research spirit, which alone makes it possible to attack the new problems fundamentally: it represents the difference between office efficiency and manufacturing efficiency. We need far more of this spirit infused into the education of the selected body of youths in our colleges and we need to offer far more encouragement to research through added endowment. Meanwhile we must be thankful to Secretary Daniels for building possibly better than he knew when he proposed the Naval Consulting Board. Their proposal of five million dollars for research seems at first an excessive expenditure, but the single item of corrosion of boiler tubes involves a direct or indirect damage of 2,000,000 dols. a year to the navy, and a single private concern manufacturing automobiles finds it economical to spend a half million dollars a year in research and experimentation.

Some of the ablest men of the country are giving their best thought to the work of this Naval Board, and it deserves the support of all of us who are in a position to appreciate its deeper significance, including its influence upon all research in both pure and applied science throughout the country.*

(NOTE.-The Federal Government is now interesting itself actively in the nitrogen question and has secured the assistance of the National Academy of Science. The