of the world's of coal

is being appreciably retarded by the electrical utilization of hitherto wasted water powers. At no distant date it may be further checked by the corresponding employment of the tides of the air and the sea. In like manner, there now emerges the possibility of maintaining indefinitely by electrical methods, for the enormous benefit of the progressive civilized races of the world, the supply of fertilizers necessary to insure steady and abundant food. Many readers of the REVIEW OF REVIEWS will remember the alarm caused in 1898 by the British Association address of Sir William Crookes, on the serious extent to which the world's wheat supply is threatened by the failing fertility of the available soil. A profound sensation was caused everywhere by that remarkable analysis of the situation. Strenuously controverted as his pessimistic assertions were, they remain broadly true; and may here be summed up in the statement that the world's low average of less than thirteen bushels per acre means literal starvation for the rapidly increasing nations of wheat eaters, unless by large access to cheap nitrogenous manures the quantity can be considerably bettered. The Caucasian has, indeed, consumed fertilizers even more extravagantly than coal and iron.

There are other ways than riotous living to waste one's substance. The nitrate deposits of Chile are swiftly running out. The guano islands are even now cleaned up. The phosphatic beds of the South are quite strictly limited. Normal resources are also squandered with criminal prodigality, and the unrequiting sea is residuary legatee of untold treasure from drains and dumps. In England alone fixed nitrogen worth $80,000,000 a year is chucked away, while the whole Atlantic seaboard of the United States testifies vividly to every eye and nose of equal waste among ourselves.

A prediction has been made that barely thirty years hence the wheat required to feed the world will be 3,260,000,000 bushels annually, and that to raise this about 12,000,000 tons of nitrate of soda yearly for the area under cultivation will be needed over and above the 1,250,000 tons now used up by mankind. But the nitrates now in sight and available are estimated good for only another fifty years, even at the present low rate of consumption. Hence, even if famine

does not immediately impend, the food problem is far more serious than is generally supposed. The starvation that we assume to be periodically inevitable in such regions as India and Russia, and which is not remote in the history of occidental Europe, looms again on the near horizon of the present century, unless we take to sundry husks that the swine do eat. Perchance, the declining increase of population shown by all recent census returns may stave off that grimly evil day. More probably, as this article will point out, relief may come from the application of new ideas and new forces to new ways of winning food. The benefactors of the race who can get three bushels of wheat where one grew before see their golden opportunity.

Dealing with the conditions as they are, Sir William Crookes pointed to an inexhaustible supply of nitrogen to be dug from the air by industry and ingenuity, with the aid of cheap power in illimitable supply, as at Niagara; and curiously enough, his prophetic surmise is already in actual realization. On every square yard of the earth's surface nitrogen gas, in the air, bears down with a weight of seven tons. What has been demanded is a method that will extract or "fix" this at little cost, and expeditiously, just as it is fixed otherwise by the infinitely minute and slow processes of nature. A building the size of the Carnegie Music Hall, in New York City, holds thus about twenty-seven tons of nitrogen, and if that were taken out of the air, and combined in the form of nitrate of soda, it would be worth $10,000.

or

Following up such calculations, Sir William Crookes has estimated that, with the electrical energy of Niagara to burn up the air, nitrate of soda ought to be producible at not more than $25 per ton. This compares, for example, with Chilean nitrate at $37.50 per ton, or the nitric acid of commerce at $80 per ton. Now the greater the consumption of Chilean nitrates Carolina phosphates the higher the price is driven; whereas, the larger the scale upon which the energy of Niagara is utilized, the cheaper the output of any plant there. The supply of air will be granted to be inexhaustible, and the available energy of Niagara is put at from five to ten million horse power; so that at the spillway of the Great Lakes alone the inventor lays his hand upon all the raw material required for furnishing

under favorable conditions whatever nitrates can possibly be needed, whether for the crops of the world or for various other important uses.

In short, with the aid of electrical-conversion apparatus, there is nothing that Niagara will fail to give us, from manure to diamonds, for just as the carbon crystals have been fixed in the fierce heat of electric furnaces, so now Mr.

MR. CHARLES S. BRADLEY.

Bradley and his associates have fixed nitrogen by a similar combination of forces. As far back as 1785, the famous Dr. Priestly noted the fact that when an electric spark was discharged through it, the air underwent immediately a chemical change. A thunderstorm and the following freshness are an analogue to this. Any one who has stood in the vicinity of frictional electric machines at work has become conscious of the pungent, fresh odor they caused; and the same phenomenon is often noticeable where dynamoelectric machinery is in motion, if the brushes on the commutator spark freely. This smell has been attributed to ozone created by the decomposition of the air and the rearrangement of the oxygen atoms; but it is now thought that it may be due, for the most part, to oxides of nitrogen. In regard to the 1785 experiments, the celebrated

physicist Cavendish said, in the quaint phraseology of the time: .. We may safely conclude that the phlogisticated air-nitrogen-was enabled by means of the electric spark to unite to, and form, a chemical combination with the dephlogisticated air-oxygen and was thereby reduced to nitrous acid; for in these experiments the two airs actually disappeared, and nitrous acid was actually found in this room."

It was, indeed, by following analogous methods that Lord Rayleigh, not long ago, was able to segregate "argon," that hitherto undetected constituent of the atmosphere. With an alternating current arc, he could effect the union of about 29 grammes of oxygen and hydrogen at the expenditure of one horse power. Nitrogen, as is well known, is present in the air in the proportion of about eight volumes to two of oxygen.

Here, then, are the foundation data of a new art; but, as usual, it is a long road from the crude experiment of the philosopher and the vivid dream of the visionary to the evolution of a practical process yielding definite commercial results. We need not wonder that over a hundred years have elapsed between the first observation and the new industrial enterprise founded at Niagara Falls by Mr. Charles S. Bradley and his fellow-worker, Mr. D. R. Lovejoy. There are even now enough philosophical records of unexploited phenomena heaped up to keep all the inventors worth their salt busy all the century founding new arts and industries on them. The problem before Messrs. Bradley and Lovejoy has consisted mainly in the production of a large number of electric arcs or flames in a confined space, through which a regulated amount of air to be burned could be passed continuously; this air emerging from the apparatus laden with nitric oxides and peroxides, as the result of the combustion, and ready for treatment and collection. It is almost needless, of course, to add that incidentally they had to attack a number of other difficulties demanding inventive ability of the highest order.

MR. D. R. LOVEJOY.

A great deal of time and money had to be spent in determining the form or variety of eleotric arc-spark that would effect the maximum chemical union of nitrogen and oxygen in the

In

the engravings herewith this chamber is shown separately and in assemblage with other parts of the apparatus. It consists essentially of a big box of metal 6 feet high and 3 feet in diameter. side is a revolving cylinder, or hollow shaft. The box has openings to admit the air and circulate it, and around its wall are rows of fixed electrical contacts for arcing points, arranged in six rows

of twenty-three each. The positive pole of the dynamo is connected in "multiple" derivation to these by wires, so as to include an inductance coil in each circuit, whose object it is to prevent the arcs from "short circuiting," and burning out, the dynamo. The negative pole or side of the dynamo circuit is connected with the revolving member inside the chamber, said cylinder