Popular Science Monthly/Volume 45/May 1894/Waste Products: Cotton-Seed Oil
By FREDERIC G. MATHER.
IT has been stated that if the waste products of the world had been saved they would sustain the present population for more than a hundred years. Foreign countries give more attention than America to saving the waste. But as the population of the United States increases, and as processes of manufacture are developed, discoveries are made which turn the waste of former products into useful articles of commerce. Glycerin, wood acid, crude petroleum, and even the fine dust from anthracite coal have an importance to-day that they did not have formerly.
Cotton-seed oil is a most conspicuous instance of an article once thrown aside as a nuisance. Originally it was only a byproduct in the manufacture of meal from the seed; and even after it was discovered that meal could be made, it was a question what should be done with the oil.
That question has been answered in various ways. What was garbage in 1860 was a fertilizer in 1870, cattle food in 1880, and table food and many things else, in 1890. A small quantity of the oil is made in England, but it is inferior to the American article because the seed comes from Egypt or India. The American cotton parts with its fiber more readily. The best oil is made from seed belonging to the Southern upland cotton, that from the seaboard having a darker color. The exports are chiefly from New York and New Orleans, and the greater part goes to France, Italy, and the Netherlands. There was a constant increase of exports between 1871 and 1884, when over 6,000,000 gallons, valued at $3,000,000, were exported. Since 1884 the export has rapidly declined, only 2,000,000 gallons, worth $1,300,000, being exported of late years, because the demand in the United States has increased.
Nine tenths of the American product enters into the composition of foods, chiefly for salad and cooking oils and for the making of refined lard. The latter use is the most important of all. Nearly forty years ago the oil was mixed with lard for use in cold climates so that the stiffening point would be several degrees lower. Lard was also prepared with this oil for the Israelites, whose religion does not permit the use of any product of the hog. The refined lard of to-day is made of refined packer's lard, pure dressed-beef fat, and pure refined cotton-seed oil. The consistence of the beef fat is overcome by the oil. Three fourths of the lard in use to-day contains from ten to twenty-five per cent of the oil, and nearly all of it is sold as oil-lard. It has been attacked by producers of hog lard, but investigations have shown that the new lard is quite as wholesome as the old.
Table oil often bears the brand of olive oil when it is really cotton-seed oil mixed with a small proportion of the olive. Sometimes the oil is taken to France and Italy and mixed there, but more often the mixture is made in this country. So closely is olive oil imitated, both as to taste and color, that only an expert knows the difference. In the earlier days of making cotton-seed oil the white oil brought a higher price than the yellow; but today the yellow oil is the more expensive. Cheaper processes of manufacture have lowered the price and encouraged the use of the yellow oil in making a substitute for butter.
Cotton oil ranks next to sperm oil and above lard oil for illuminating purposes, and it may be burned in any lamp used for either. Mixed with petroleum, it increases the freedom of burning; but this requires a change in the wick. As a lubricating oil cotton-seed is useless, because it is half way between the drying and the non-drying. For the same reason it can not be used for paints, for wood filling, or for leather dressing. It has some use as a substitute for vaseline and similar products. The oil enters into the production of laundry and fancy soaps and soaps for woolen mills. The American sardines, properly known as young shad and herring, are put up with this oil, and the use of it extends so far that nearly all the real sardines of Europe are now treated in the same way. The oil forms an emulsion in medicine and a substitute for cod-liver oil. On the market the crude oil is known as either prime, or off quality, or cooking. There are also the white summer, the yellow winter, and the white winter. All these, except the crude, bring an average of about fifty cents a gallon in the wholesale market. After the oil has left the seeds, they become food for stock in the shape of oil cake, while the ashes from the hulls make a fertilizer for root crops.
The first attempt to extract oil from cotton seed was made in Natchez, Miss., in 1834. The machinery of the mill was of the most primitive kind, the pressure being given by wedges. Failure attended this effort, and also an effort in 1852 with improved machinery. In 1855 cotton seed began to have a commercial value. Small mills were established, and the prospects for developing the industry were good until the breaking out of the civil war cut off the supply of seed. Directly after the war, in 1866, there were only seven mills in the whole country. Three of them were in New Orleans, one in Providence, one in Cincinnati, one in Memphis, and one in New York. In 1870 there were twenty-six mills; in 1880, forty-five; and in 1890, two hundred and twenty-five all but two being in the Southern States, as follows: Alabama, thirty; Arkansas, twelve; Florida, three; Georgia, thirty-nine; Louisiana, fifteen; Mississippi, twenty-three; North Carolina, twenty; South Carolina, thirty-four; Tennessee, twenty; Texas, twenty-seven. The highest capacity of any of the mills is 320 tons daily; and for all the mills, 7,636 tons daily, or 2,367,160 tons annually. None of them are operated on full time, and most of them run only three or four months during the height of the cotton season. The mills are of all sizes, and they range from $5,000 to over $250,000 in value.
The output of cotton-seed products was valued at $600,000 in 1860, $2,205,000 in 1870, $7,691,000 in 1880, and nearly $22,000,000 in 1890. Since that date the product has fallen off. The details for 1890 were: 28,000,000 gallons of crude oil; 17,000,000 pounds of cotton batting; 283,000 tons of oil cake; 378,000 tons of hulls, ash, soap-stock, and other by products; and $2,853,000 of enhanced value in refining the oil and manufacturing the soap. The Southern States produced 2,870,417 tons of cotton seed in 1880, of which barely one eighth was crushed in the mills. The yield of seed during the past five years has been as high as 3,600,000 tons; but only one fifth of it reached the mills. The American Cottonseed Oil Company, formerly known as the Cotton Trust, owns the entire capital stock of ninety-five factories, a small portion of which are not in operation. The factories include not only crude-oil mills, but mills for the production of fertilizers, soap, and the other products. The total business for the year ending November 1, 1889, the best in the history of the mills, was about $25,000,000. An improved method of crushing gave better results than for any previous year. At first the oil was transported from the mills in barrels, but now a great saving is effected by the use 6i tank cars.
When the season is not dry the seed is rich in oil, and it yields readily thirty-five or more gallons to the ton. An unfavorable season reduces the yield to thirty-one gallons. When the seed is well stored and properly ventilated, it will keep for a year; it is liable to become rancid in the hold of a vessel. If stored long in bulk, it becomes superheated and liable to spontaneous combustion. These facts prevent exportation in large quantities. The cotton plant yields an average of nine hundred and fifty pounds of seed to each bale of cotton. The price of seed has been as high as seventeen dollars a ton, but there is no profit to the millers if they pay much over twelve dollars. A sharp competition among them led to the forming of an association of the mills in 1878, which was the forerunner of the American Cotton-seed Oil Trust. The Southern States are now divided into districts, each one supplying certain mills, and keeping a uniform price for the seed.
The bulk of the supply is obtained from plantations immediately upon the Southern rivers, because the seed can be transported at little cost. The mills are also located upon the rivers. Once landed at the mills, the seed is conveyed in an elevator to a screen, or cylindrical sifter, where it is shaken until it is free from dust and sand. Then it is blown against another screen to remove stones, iron, and other foreign substances that might injure the rollers. A second elevator carries the seed to the loft, where another sifter separates the seed proper from the bolls or outside hulls of the cotton bloom. No matter how close the picking may have been, the bolls still have cotton sticking to them, and they are dropped into a gin to remove the lint. This is known as "crapo cotton," the only variety of linter produced in the mills. The seed having fallen through the screen, is carried along another screen or gutter directly over the gins. They drop through holes in the screen upon the gins; but when the box above the gin is full the hole is closed automatically, and the screen carries the seed forward to the next box, thus keeping all the boxes full. The gins differ from cotton gins in having one hundred saws instead of sixty. The saws are but half an inch apart and the teeth are very firmly set. The problem of wholly removing the lint, save by chemical process, has not yet been solved.
Once thoroughly separated from all foreign substances—dust, bolls, and cotton—the seed is conveyed to the roller, a revolving cylinder containing twenty-four knives and four back knives, which cuts the hulls from the kernels. This process was formerly carried on by grindstones. The hulls go upstairs, where they are again treated to find such kernels as may still be clinging to them, after which they are sold or used as fuel in the furnace of the mill. Only half of them are needed for this purpose, the other half being sold as food for cattle. The ashes of the hulls make an excellent lye for soap or for the refining of the oil. The kernels are conveyed to rollers, where they are crushed very fine. They are thence removed to the heaters, being agitated all the time so as to give an equal exposure and allow the oil to be more readily extracted. The kernels are then placed in woolen bags packed between horse-hair mats, backed with leather, and having a fluted surface inside to allow the oil to escape more freely. The hydraulic pressure, furnished by the oil itself instead of by water, is from one hundred and fifty to two hundred and fifty tons.
The bags are in the press about fifteen minutes, the oil running out and the dry kernels remaining behind in a solid cake—the oil cake of commerce. This product is of a rich golden color, quite dry, and of a sweet and oily taste. When used for food it is ground to the consistence of corn meal, and it is known as cotton-seed meal. A comparison of the number of pounds of flesh produced by several kinds of food is as follows: Cotton-seed cake, forty-one pounds; bran, thirty-one pounds; peas, twenty-two pounds; corn, twelve pounds; rye, eleven pounds. The number of pounds of fat produced by the several foods are these: Cotton-seed cake, fifty-seven pounds; bran, fifty-four pounds; peas, fifty pounds; corn, sixty-eight pounds; rye, seventy-two pounds; hay, fifty pounds. It is claimed that cotton-seed cake fed to cows gives a rich and plentiful supply of milk.
The oil, having been pumped into the oil room, is treated with caustic soda and constantly stirred. A deposit falls to the bottom of the kettle and the refined oil is turned off. It averages about eighty-two per cent of the crude oil. The deposit, known as soap stock, sells readily to soap manufacturers, or it is used by the mill itself in the manufacture of soap. Much of it is sent to foreign countries. The oil is occasionally refined over again to remove wholly a slightly bitter flavor of the seed which reduces the culinary value.
It will be noticed that the products of the seed are—(1) oil, both the crude and the refined; (2) oil cake; (3) lint; (4) hulls; (5) soap stock; (6) glycerin. One gallon of crude cotton-seed oil will yield three pounds and a half of glycerin, but thus far only a small amount has been made. The use of the seed for these several purposes has been of great benefit to the Southern States. Their output is constantly increasing, while the supply of petroleum in the oil fields of Pennsylvania and elsewhere appears to be decreasing. The world was greatly excited when petroleum was discovered. But the discovery of cotton-seed oil has been so gradual that the importance of it has not been realized until lately. This brief statement of what is being done to-day with an article that was going to waste a generation ago must lead every student of economy to ask, "Are there not other waste products of the present time that will be used a generation hence, and thus not only increase the comfort of living but also decrease the expense?"