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TOP OF THE ABSORPTION TOWERS, SHOWING APPARATUS FOR THE DISTRIBUTION OF THE

WATER AND MILK OF LIME.

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TARVATION may be problem as to how to meet the growing averted through the labo- demand that has resulted from the exratory.” Such were the tensive developments of agriculture, for momentous, prophetic nitrogenous foods. The population of words of the eminent sci- the globe is rapidly becoming more and

entist, Sir William Crookes, more dependent for its vital force upon before the annual congress of the Brit- what the scientists generically term ish Association in 1898, and he ventured bread—that is, those foodstuffs essento prophesy also that it would be the tially of a highly nitrogenous character. combination of chemical research and the The existence of all life both animal and hydraulic forces of nature, as exempli- plant is absolutely dependent upon a cerfied in the numerous water-falls, that tain number of substances generally would, at no distant time, be used to pro known as the aliments, and the presence duce an adequate food-supply for the of nitrogen in some form in these aligrowing population of the world.

ments is indispensable. It is the atmosThe one great question that has been phere which directly or indirectly furdirecting the closest research of the nishes to all living things the nitrogen whole scientific world for more than a necessary for its life, and it is from the century past has been the solving of the air, moreover, that the two principal forms of nourishment which agriculture Cavendish ascertained that the nitrogen demands in the combinations of its fer- present in the air is oxidable under the tilizers, nitrate of soda and sulphate of influence of the temperature produced by ammonia, are derived.

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PHOTOGRAPH OF THE DISK OF FLAME PRODUCED IN A

the combustion of the hydrogen in the At the present time the agricultural in- atmosphere, and that when this latter gas dustry depends almost entirely for the is ignited by the electric spark the result former of these two substances for plant of such combustion, by the contact of the life, upon the nitrate of soda deposits to be found in Chile, but the supplies available from that country are by no means adequate for our needs. Under these circumstances in order to avert that famine which Sir William Crookes in concert with many other distinguished savants predicts as being in store for the world, further sources of supply have become urgently requisite. In view of the fact that the atmosphere surrounding us is roughly composed of seventy-nine parts of nitrogen to twenty-one of oxygen—which overwhelming preponderance of the first named element demon

BIRKELAND-EYDE ELECTRIC FURNACE. strates the extent of our dependence upon nitrogen—it will be seen that an oxide of nitrogen with the water, is nitric enormous quantity of this gas envelopes acid. the earth. Consequently it is only nat- During the past few years several atural that scientific investigation should tempts to turn Cavendish's momentous endeavor to find some means of produc- discovery to practical account have been ing nitrates from these immediately ac- made, but success has been only medicessible reserves. The economical and ocre, and not sufficient to warrant the commercial practicability of such a commercial use of the system. Two great scheme in the interests of science, in- difficulties confront the realization of dustry, and agriculture opens up vast such a project, as these exploiters have possibilities.

found to their cost. In the first place, Ever since Cavendish first discovered owing to the fact that the yield of nitric the presence of hydrogen gas and the oxide per unit of electric power concombustibility of this gas—which when sumed is so small, the process is impracignited in the atmosphere gives rise to ticable unless an abundant and cheap supwater—as far back as 1781, scientists ply of electric energy is available, such have been wrestling with this problem. as is afforded by water power; and in the

second place, owing to the fact that the thermal action, which produces the union of the nitrogen and oxygen by sparking, is reversible in its action—i. e., the same heat which produces the nitric oxide will also cause its dissociation unless it is speedily removed from the influence of the electric spark. It is this second factor which has caused

efforts to use CavenCOMPARATIVE Growth OF PLANT LIFE UNDER NITRATE FERTILIZATION. The tallest plants, just left of the center, were fertilized with the British nitrates. dish's discovery and to

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produce nitric acid with its aid to end and so on with such tremendous frein failure.

quency that the resultant effect was a Recently, however, a new system of brilliant half-round flame, it being posaccomplishing this ideal has been evolved sible to strike several hundred arcs per by two eminent Norwegian scientists, second. With a continuous current it Dr. Birkeland and Mr. Eyde, which has was observed, however, that the halfbeen reduced to a successful and com- disk of flame was always produced upon

one side, so in order to obtain a more or less completely round flame Dr.Birkeland resolved to test the phenomenon with an alternating current of very high tension. The result was as anticipated, the arc being struck alternately on each side of the electrode and with such rapidity that the flame was almost circular in shape. In this experiment he also made another important discovery. Whereas with the continuous current, as the voltage was increased so was the volume of the noise caused by the sparking, but with the alternating current the sound produced was decreased, suffused, and quite different in character from that produced

with the direct current, because here the SEMI-Dısk OF FLAME PRODUCED BY CONTINUOUS ELECTRIC CURRENT.

number of cycles of the alternating

current combined with the intensity of mercially practicable basis. In this proc- the electro-magnet exercised a peculiar. ess the secret and vital factor is the influence upon the phenomenon. In one means adopted for the speedy removal of the accompanying photographs is of the nitric oxide formed by the electric shown such a disk of Aame produced in a spark, from the proximity of the latter, 250-horse-power Birkeland-Eyde electric whereby the dissociation of the nitrogen furnace, the disk being produced with an and oxygen is prevented. In the course alternating current of 50 cycles per of an experiment with a continuous elec- second with a tension of 5,000 volts. tric current of forty amperes, 600 volts For the oxidation of the atmospheric tension, Professor Birkeland accidentally nitrogen by means of the electric arc, established contact between the adjacent Messrs. Birkeland and Eyde designed a metallic pieces of the apparatus, which special type of furnace, which possesses resulted in the production of an intensely several ingenious features and in which powerful magnetic field. As the points have been embodied the results of the were brought into contact a sharp explo, many observations concerning the varision was developed and a flat flame semi ous and peculiar chemical and electrical circular in form and about 3.9 inches in diameter was produced. He followed up this phenomenon with a further experiment in which he used a current of only two amperes taken from a continuous current dynamo and intensified to 3,000 volts. The contact pieces or electrodes were placed at right angles between the poles of a powerful electro-magnet and resting about .08 inch apart. When the arc was struck there was produced an intense spark the peculiarity of which was that it traveled backwards along each electrode until it broke. Instantly another spark followed in like manner

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COMPLETE DISK OF FLAME PRODUCED BY ALTERNATING

CURRENT

CROSS SECTION OF THE BIRKELAND-EYDE FURNACE FOR

PRODUCING NITRATES FROM THE ATMOSPHERE,

actions that take place in the oxidation of the nitrogen. In this furnace which is of especially stout construction to ensure durability, the electrodes are made of hollow copper tubes .59 inch in diameter, internally cooled by water, and placed two millimeters apart. The atmosphere from which the nitric oxide is to be formed is forced into the internal space of the furnace surrounding the points of the electrodes through a series of channels, and directly the oxygen und nitrogen have been united forming nitric oxide by passing through the electric flame, the gas is swept away through two other canals for the subsequent phases of the process. The stout construction of the furnace and the long life of the electrodes—several hundred hours—constitute a prominent feature of the process and are of considerable economical importance, reducing to an appreciable ex- The installation at Notodden is actent the initial outlay for the apparatus commodated in four large buildings situand also the expense of maintenance. ated close together and inter-communi

When the inventors had sufficiently cating. The first building contains the perfected their process to enable it to be electric furnaces in which the nitrogen is commercially applied, a small installation oxidized; the second the absorption towwas laid down in 1903 at Frognerkillens, ers in which the production of the nitric in Norway. This was a plant of twenty- acid from the nitric oxide is carried out; . five horse-power and an alternating cur- the third is devoted to the manufacture rent of 5,000 volts was utilized. Three of the nitrates of lime, soda, and potash months later a larger plant became neces- by the combination of the nitric acid ; sary and this was completed at Anker- while the fourth is reserved for storing, lokken, the energy being increased to 150 packing and shipping the various prodhorse-power. Developments, however, ucts. followed so rapidly that a still larger in The electrical equipment comprises stallation became requisite and this was three furnaces of identical design concarried out at Vasmöen, being of 1,000 structed in accordance with the principles horse-power, while a few months ago a enunciated by Messrs. Birkeland and fourth and still larger plant was laid Eyde. They are the largest that have down at Notodden for the commercial yet been constructed for this purpose, production of the nitrates upon an exten- being from 500 to 700 kilowatts capacity sive scale, the energy in this instance ag- each. The necessary energy is derived gregating 2,500 horse-power. These from the neighboring river Tinnfos, and works are now in full operation and al- is obtainable at a cost of $3.20 per kiloready extensive additions are in prog- watt-year. ress for the development of the industry The atmospheric air is fed into the and the increase of the output. Several furnaces through shafts or conduits by eminent scientists and physicists of means of fans at the speed of nearly 900 various nationalities have visited the cubic feet per minute, making for the Notodden plant to study and follow the three furnaces an aggregate consumption various details of the process, and from of 2,600 cubic feet, or 75 cubic meters of the results of their observations it is gen- air per minute. After passing through erally conceded that a successful and the flame of the arc, the oxidized nitrogen commercially practicable solution of the is gathered in a novel canal collector at prophesy made by Sir William Crookes a temperature ranging between 500 and is in a fair way toward being fulfilled. 700 degrees Centigrade. As this tem

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