other hand, the competition of the two rival artificial manures is likely to diminish as the years pass on.

"The new industry is, therefore, likely to be a permanent addition to the list of electro-metallurgical processes. But for the present its success can only be expected in centres of very cheap water-power, as, for instance, in those localities where the electric horsepower year can be generated and transmitted to the cyanamide works at an inclusive cost of £2 ($10) or under."

ELECTRICAL ENERGY AND HIGH TEMPERATURES

It will be observed that the active instrumentality by which the industrial feats thus far outlined have been accomplished, is that weird conveyer of energy known as electricity. In the case of the aluminum manufacture, electricity operated according to the strange process of electrolysis, in virtue of which certain atoms of matter move to one pole of a battery while other atoms move to the opposite pole, thus effecting a separation-the result being, in the case in question, the deposit of pure aluminum at the negative pole. In the case of the nitrogen factories, however, the manner of operation of the electric current is quite different. Electricity, as such, is not really concerned in the matter; the efficiency of the current depends solely upon the production of heat. For example, any other agency that brought the atmosphere to a corresponding temperature would be equally efficacious in igniting the nitrogen. But in actual practice, for this particu

lar purpose, no other known means of producing high temperatures could at all compete with the electric arc.

There are numerous other operations involving the employment of high temperatures in which electricity is equally preeminent. It is feasible with the electric arc to attain a temperature of about 3,600 degrees centigrade and even this might be exceeded were it not that carbon, of which the electrodes are composed, volatilizes at that temperature. Meantime, the highest attainable temperature with ordinary fuels in the blast furnace is only about 1,800 degrees; and the oxy-hydrogen flame is only about two hundred degrees higher. A mixture of oxygen and acetylene, however, burns at a temperature almost equaling that of the electric arc; and this flame, manipulated with the aid of a blowpipe, offers a useful means of applying a high temperature locally, for such processes as the welding of metals. The very highest temperatures yet reached in laboratory or workshop, however, are due to the use of explosive mixtures. Thus a mixture of the metal aluminum granulated, and oxide of iron, when ignited by a fulminating powder, readjusts its atoms to form oxide of aluminum and pure iron, and does this with such fervor that a temperature of about three thousand degrees is reached, the resulting iron being not merely melted but brought almost to the boiling point. Practical advantage is taken of this reaction for the repair of broken implements of iron or steel, the making of continuous rails for trolleys, and the like.

This reaction of aluminum and iron does not, to be sure, give a higher temperature than the electric arc; but this culminating feat has been achieved, in laboratory experiments, through the explosion of cordite in closed steel chambers; the experimenters being the Englishmen Sir Andrew Noble and Sir F. Abel. It is difficult to estimate accurately the degree of heat and pressure attained in these experiments; but it is believed that the temperature approximated 5,000 degrees centigrade, while the pressure represented the almost inconceivable push of ninety tons to the square inch.

It may be of interest to explain that cordite is a form of smokeless powder composed of gun cotton, nitroglycerine, and mineral jelly. No doubt the extreme heat produced by its explosion is associated with the suddenness of the reaction; corresponding to the efficiency as a propellant that has led to the adoption of this powder for use in the small arms of the British Army. No commercial use has yet been made of cordite as a mere producer of heat; but there is an interesting suggestion of possible future uses in the fact that crys tals of diamond have been found in the residue of the explosion chamber-microscopic in size, to be sure, but veritable diamonds in miniature. Sir William Crookes has suggested that, could the reaction be prolonged sufficiently, "there is little doubt that the artificial formation of diamonds would soon pass from the microscopic stage to a scale more likely to satisfy the requirements of science, if not those of personal adornment."

OTHER INDUSTRIAL PROBLEMS OF TO-DAY AND
TO-MORROW

In attempting to suggest the importance of science in its relation to modern industries, I have thought it better to cite three or four illustrative cases in some detail rather than to attempt a comprehensive summary of the almost numberless lines of commercial activity that have a similar origin and dependence.

To attempt a full list of these would be virtually to give a catalogue of mechanical industries. It may be well, however, to point out a few familiar instances, in order to emphasize the economic importance of the subject; and to suggest a few of the lines along which present-day investigators are seeking further conquests.

Very briefly, then, consider how the application of scientific knowledge has changed the aspect of the productive industries. Thanks to science, farming is no longer a haphazard trade. The up-to-date farmer knows the chemical constitution of the soil; understands what constituents are needed by particular crops and what fertilizing methods to employ to keep his land from deteriorating. He knows how to select good seed according to the teaching of heredity; how to combat fungoid and insect pests by chemical means; how to meet the encroachments of the army of weeds. In the orchard, he can tell by the appearance of leaf and bark whether the soil needs more of nitrogen, of potash, or of humus; he uses sprays as a surgeon uses

antiseptics; he introduces friendly insects to prey on insect pests; he irrigates or surface-tills or grows cover crops in accordance with a good understanding of the laws of capillarity as applied to water in the earth's crust. In barnyard and dairy he applies a knowledge of the chemistry of foods in his treatment of flock and herd; he ventilates his stables that the stock may have an adequate supply of oxygen; he milks his cows with a mechanical apparatus, extracts the cream with a centrifugal "separator," and churns by steam or by electric power.

In the affairs of manufacturer and transporter of commodities, methods are no less revolutionary. Steam power and electric dynamo everywhere hold sway; trolley and electric light and telephone have found their way to the most distant hamlet; electricians and experimental chemists are searching for new methods in the factories; artificial stone is competing with the product of the quarries; artificial dyes have sounded the doom of the madder and indigo industries.

And yet it requires no great gift of prophecy to see that what has been accomplished is only an earnest of what is to come in the not distant future. In every direction eager experimenters are on the track of new discoveries. Any day a chance observation may open new and important fields of exploration, just as Hall's observation about the power of cryolite to absorb aluminum pointed the way to the new aluminum industry; and as Birkeland's chance observation of the electric arc in a magnetic field unlocked the secret of the unresponsive nitrogen. It will probably not