From the Air* of nitrogen and you can take off twenty pounds more wheat and forty pounds more straw than you could if you failed to make this application. One pound of nitrogen properly applied to a cornfield will add thirty-five pounds to the crop; one pound of nitrogen will produce one hundred pounds of increase in the potato crop; one pound of nitrogen will produce five pounds of cotton, without any extra labor being devoted to the production of the crop. Nitrogen is the heart and soul of the problem of growing more crops and cheaper crops. Take any nation that produces large crop yields per acre and you will find that the nation that uses the most nitrogen per acre grows the largest crops.

What is the greatest discovery of the last twenty-five years? Probably you will say the wireless telegraph, the flying machine, moving pictures or the phonograph, but it would be none of these, according to the Scientific American. This publication discussed at great length the subject of what invention of the last twenty-five years was of greatest value to mankind. First place was given not to the wonderful inventions that are so large in the public eye, but to the fixation of nitrogen from the air for fertilizer purposes. Why? Simply because this discovery stands between man and starvation. Other inventions are vastly important, but this one is vital. Looking at it from the broadest view there can be no other decision. The time is here when to feed the world is becoming a more and more difficult problem.

During the past ten years our population has increased at the rate of two per cent per annum, while our crop production has increased only one-half as fast. In six years the number of beef cattle produced in this country has fallen off about five per cent per annum. The cost of foodstuffs recently has been increasing at the rate of five per cent per annum. The hardships experienced by wage-earners, particularly in the United States, have been very great in view of the fact that the cost of food increased more rapidly than wages - at a rate approximately double. The same tendencies apply with some modifications to the clothing of mankind. These facts point to the necessity of increasing the yields both of the food crops and the crops that are used in the making of clothing.

The problem of decreasing the cost of living has been given far more attention abroad than it has in this country, owing to the much greater density of population in the principal nations of Europe. For a long time it has been known that plants require food the same as animals and human beings. Without food plants cannot live and grow, and just to the extent that plant food is present in the soil, to that extent will a crop be produced. The most important of plant foods is nitrogen. While the earth is literally bathed in nitrogen, this element is found to only a very slight degree in the soil. That is to say, the air which we breathe and in which we move is four-fifths nitrogen, yet in the richest soil there is seldom more than one-tenth or two-tenths of one per cent of nitrogen. Put on a wheat crop one pound

Wrapper Leaf Tobacco Crop Fertilized with Cyanamid Mixtures. Grown in Hatfield, Mass..

*Illustrations by courtesy of American Cyanamid Company.

For years the nations of Europe have been depending to a great extent upon supplies of nitrate of soda obtained from Chile, in South America. Germany alone imported nearly a million tons of this salt annually before the war. Then, too, the by-products of many industries furnish a quantity of nitrogen, but all this, it was realized, furnished but a small part of what was required to combat the constantly rising cost of producing food.

For years it was the dream and life-ambition of the world's greatest scientists to discover how to make the supplies of nitrogen in the air available to plants as food. The only way that this could be done in nature was through the agency of bacteria working on the roots of certain plants, such as clovers, but this process was entirely too slow for practical purposes and could be applied on only a small acreage at one time. The free nitrogen of the air cannot be utilized directly by plants. It must first be converted into some combination with other chemicals, as a solid or liquid, which can be absorbed by the plant. Among others who worked on the problem of fixing atmospheric nitrogen were two German chemists, Doctors Caro and Frank, who found that a compound of calcium and carbon heated to a high temperature would absorb nitrogen and retain it in a form that could be applied to the soil and serve as a food for plants.

This discovery is the basis of the Cyanamid "Atmospheric Nitrogen" industry or the making of fertilizer from the nitrogen in the air. After the discovery was made and tested on the laboratory scale it took several years to put it on a practical basis, as can well be imagined when it is understood what the problems involved were. Besides air this process required as raw materials limestone and coke. The limestone must be burned to quicklime and the quicklime and coke must be fused together to form calcium carbide. Only the most powerful electric furnaces are capable of performing this work. Any other means of heating is far from adequate. For instance, the hottest flame that can be produced by the burning of gas, namely, the oxy-hydrogen blow-pipe flame, can be directed against a stick of burnt lime without doing anything beyond making the lime glow brilliantly, thus producing the caiciam or lime-light formerly much used in theaters as a spot-light. In the electric furnaces, however, the lime is heated so powerfully that it actually melts to a liquid, and in this condition it dissolves the coke with which it is mixed and the compound resulting is calcium carbide which can be run off from the interior of the furnace in liquid form.