Sugar Cane Crop Fertilized with Cyanamid Mixtures..

Grown in Calumet, La.

At the cyanamid plant at Niagara Falls, in Canada, there are seven of these great carbide furnaces, each about fifteen feet long and half as wide and one-third as deep. We all have some idea of how much heat is generated in the ordinary electric arc light such as is used for street lighting. In the carbide furnace the carbon pencil, instead of being six or eight inches long and as large around as your finger, is six feet long and two feet in diameter. There are three of these in each furnace, and when the furnace is in full action it can be imagined that there is a terrific heat generated; in fact, when the fused lime and coke come out of the furnace in the form of molten carbide the brightness of the molten material is so dazzling that one cannot look at it with the naked eyes without injury.

Then there is the problem of producing pure nitrogen gas, that is, separating the eighty per cent of nitrogen in the air from the twenty per cent of oxygen. The latter is the element that we breathe and which passes into the body, there to combine with the impurities resulting from the various life activities. If the nitrogen and the oxygen were both allowed to act upon calcium carbide the oxygen would burn up the carbide before the nitrogen could be fixed in it, hence these two elements must be separated and all other impurities removed so that only chemically pure nitrogen is brought to the calcium carbide for fixation. The separation is accomplished by means of liquid air machines. This industry, therefore, not only utilizes the greatest heat obtainable on a practical scale, but it also utilizes the greatest cold. While the electric furnaces produce a temperature of over 4000° F., or about twice as hot as molten cast-iron, the liquid air machines work at a temperature of 372° F. below zero. The air must first be purified and dried. It is then compressed, cooled while under pressure, and then expanded. The expansion lowers its temperature considerably. If this extra cool air is used for cooling another batch of air under pressure, the latter upon expansion becomes still colder than the first batch expanded. By repeating this operation the final temperature of 372° below zero is reached, at which the air liquifies.

Two of the Carbide Furnaces and Electrode Regulators.

One of the Carbide Mills.

How cold this is can be seen from some simple experiments. For instance, if a dipper full of the liquid air is drawn, in an instant the outside of the dipper is covered with a coating of frost deposited upon it from the surrounding atmosphere. The surrounding air is so much hotter than the liquid air that the liquid boils violently. If a piece of rubber hose is held in the liquid air for eight or ten seconds and then struck with a hammer the rubber flies into pieces just like glass. To dip one's finger into this liquid air would freeze it solid in a second and would be as disastrous as dipping it in red-hot iron.

When the liquid air is allowed to warm up a little, the nitrogen gas evaporates, while the oxygen remains behind in the liquid. The pure nitrogen then can be pumped into the fixation ovens.

To fix the nitrogen in the carbide it is necessary to cool the latter after it comes from the electric furnaces and grind it to a very fine powder. This powder is then placed in furnaces that look like steel barrels but are three or four times larger than an ordinary barrel. The oven filled with calcium carbide is then electrically heated with a carbon rod running through the center. When the temperature is about as hot as that of molten iron the pure nitrogen gas from the liquid air plant is pumped in and allowed to act on the calcium carbide for about a day and a half. When the carbide has absorbed all it will absorb the crude cyanamid formed is removed from the oven as a single large cake which is run through pulverizing drums and then put through an elaborate process of refinement and finally bagged for shipment in carload lots to fertilizer factories throughout the country.

The fertilizer manufacturers mix the cyanamid with other ingredients to make a balanced plant food and so ship it to farmers for feeding their crops. In 1914 7,500,000 tons of fertilizer worth $175,000,000 were consumed in this country. This seems like a large quantity, but it allows only a scanty application per acre cultivated. Germany, on one-fourth of our cultivated acreage, uses almost twice as much fertilizer as the entire United States. As a consequence she raises 30 bushels of wheat where we average 14 bushels per acre; 52 bushels of oats where we average 30; and 196 bushels of potatoes per acre where we raise 97 bushels per acre. The explanation is simple, German farmers pay only about one-half as much for their plant food as American farmers pay. Where the German farmer gains $2.00 to $3.00 increase in crop from fertilizer that costs him $1.00 the American farmer pays $2.00 for the same fertilizer, which leaves him less profit and less incentive to use fertilizer.

The air-nitrogen industry in the United States is said to be considerably handicapped because the large quantities of electricity required are not available at a low enough price. There are excellent water-power sites in the United States sufficient

Liquid Air Plant.

A Carbide Cooling Shed.