SODIUM BENZOATE. [This sodium salt is a coal-tar compound. It is provided for in H. R. 8078. See following reports of Tariff Commission. Dyes and Other Coal-Tar Chemicals. Census of Dyes and Coal-Tar Chemicals, 1917, 1918, and 1919.] SODIUM BICARBONATE. [Par. 67, act of 1913. One-fourth cent per pound.] SUMMARY. Description.-Bicarbonate of soda or acid sodium carbonate is the mildest of the alkalies. It contains about 36.9 per cent of alkali (Na2O). In the pure form it is the common baking soda. Sodium bicarbonate is the cheapest and most convenient form of storing carbon dioxide. It is used in the manufacture of baking powders, seidlitz powders, effervescing drinks, in charging fire extinguishers, and for many household purposes. Domestic production. The production of sodium bicarbonate has increased from 90,169 short tons valued at $1,439,014 in 1914 to 174,212 short tons valued at $5,292,374 in 1917. The 1919 output was 134,962 short tons valued at $3,486,635. This domestic production supplies practically all of our consumption. Salt, lime, ammonia, and coal are the raw materials required for the manufacture of bicarbonate of soda, all of which are available in large quantity in this country. The ammonia is recovered and used repeatedly. The plants manufacturing bicarbonate of soda are located near deposits of salt, the basic raw material. Refined bicarbonate of soda for baking purposes is produced at Syracuse, N. Y.; Saltville, Va.; and Wyandotte, Mich. At these plants it is one of the products of the Solvay ammonia-soda process, the other products being sodaash and caustic soda. A small quantity is produced from the waters of Owens Lake, Calif. The production of bicarbonate of soda involves large-scale continuous operation, the materials being handled principally by labor-saving mechanical devices. A plant for producing bicarbonate of soda requires a large initial outlay of capital and a highly developed organization. Imports. The imports of sodium bicarbonate have been small compared with our production. The maximum imports since 1910 were in 1916, amounting to 129,414 pounds, valued at $2,867. In 1917 they fell off to 34,742 pounds valued at $1,821. Prices. The price of bicarbonate of soda has about doubled since the outbreak of the war. This is not as great an increase as the other alkalies have undergone, probably due to the fact that bicarbonate of soda is not as important industrially as the other alkalies. Tariff history.-Bicarbonate of soda has paid a specific duty varying from 1 cents per pound by the act of 1883 to pound by the act of 1913. Sodium bicarbonate-Summary table. cent per 2 From Aug. 6, 1909, to June 30, 1910. 3 From Oct. 4, 1913, to June 30, 1914. In the period from July 1 to Oct. 3, 1913, there were imports valued at $629, equivalent ad valorem of 26.02 per cent, and duties of $163. GENERAL INFORMATION. Description and uses.-Bicarbonate of soda, or acid sodium carbonate, is the mildest of the alkalies. It is composed of 36.9 per cent of sodium oxide (Na2O), 52.4 per cent of carbon dioxide (CO2) and 10.7 per cent of water (H2O). It is a white opaque powder which is soluble in water. In the pure form bicarbonate of soda is the common baking soda. When heated, either in the dry form or in solution, sodium bicarbonate loses half of its carbon dioxide with the formation of soda ash. When treated with an acid it loses all of its carbon dioxide; it is this property of evolving its carbon dioxide that gives bicarbonate of soda its use for industrial and household purposes. Sodium bicarbonate is the cheapest form of storing carbon dioxide and it is also the most convenient. It is used in the manufacture of baking powders, Seidlitz powders, effervescing drinks, and is used in medicine as a remedy for acidity of the stomach. It is also used in the household for destroying the acidity of sour milk and other articles of food. A very pure product is demanded for the above household and medicinal purposes. A product of less purity is used for producing carbonic acid for the carbonating of waters, for charging fire extinguishers, and for the prevention of timber mold. Mixtures of sodium bicarbonate and sodium carbonate (soda ash) are sold as "modified or neutral sodas. These mixtures are usually used for cleaning purposes. Raw materials-Salt in the form of brine, lime, ammonia, and coal are the necessary materials required for the production of sodium bicarbonate by the "ammonia-soda" process. The ammonia is used over and over again so that it is only necessary to supply the losses in process which are relatively small. The lime is usually burnt at the plant, so that the carbon dioxide evolved is available for use in the "ammonia-soda" process. The lime is used for the regeneration of the ammonia and for the manufacture of caustic soda which is usually produced in conjunction with an ammoniasoda" plant. The brine should be of a good grade and particularly should not contain an appreciable amount of magnesium, which will cause trouble in the process. All of the raw materials necessary for the manufacture of sodium bicarbonate are available in large quantities in the United States. The industry is therefore independent of any foreign country so far as the raw materials are concerned. Process of manufacture. The basic raw material salt is first dissolved to form a concentrated brine solution. For the economical operation of this process the factories are located where the salt can be pumped as a saturated brine from the salt beds in the immediate neighborhood. This brine solution is then saturated with ammonia gas. The ammoniacal brine is then treated with carbon dioxide in a high tower. The main reaction occurs in these towers with the formation of bicarbonate of soda, which separates out as it is insoluble in the solution of ammonium chloride which is produced simultaneously. The precipitated sodium bicarbonate works its way down the tower and is finally drawn off at the bottom in the form of a white milky liquid containing the bicarbonate in suspension. The bicarbonate of soda is separated from the mother liquor by filtration and is purified by washing. The ammonia is recovered from the mother liquor and wash waters by treating with lime. The crude bicarbonate of soda thus produced ordinarily contains too much ammonia to be used as baking soda or in the manufacture of baking powders. It is found that drying this crude bicarbonate of soda to remove moisture does not remove the ammonia and if heated sufficiently to remove the ammonia the bicarbonate is partially decomposed into soda ash. The crude bicarbonate is, therefore, converted first into soda ash by calcination. (See Tariff Information Survey on Sodium Carbonates.) The soda ash is then dissolved in water and carbonic acid gas is passed through the solution, thus producing a refined bicarbonate of soda. Before the introduction of the "ammonia-soda" process, sodium bicarbonate was made from soda crystals by treating them with carbon dioxide in suitable apparatus. This process is not in general use in this country. Bicarbonate of soda is manufactured from the waters of Owens Lake, Calif., by passing carbonic acid gas through the water in a tower. Operations are carried on only during the season from April 1 to November 1. During the winter months the alkali separates out in the lake in the form of trona (Na,CO,. NaHCO,. 2H2O) and so reduces the alkali content of the water that it is not suitable for the manufacture of bicarbonate of soda. History of the industry.—The history of the manufacture of bicarbonate of soda practically parallels that of soda ash as the two products are very closely allied. (See the report on Soda Ash.) The development of the baking powder industry using sodium bicarbonate as the active constituent has been the greatest in the United States, as there has been very little development of this industry in Europe. Even before bicarbonate of soda was made in this country, baking powders were manufactured in the United States from sodium bicarbonate imported from England. Bicarbonate of soda—Production in United States. Sodium bicarbonate-Exports of the United Kingdom. Quantities are in short tons of 2,000 pounds. Table is taken from the official report of the United Kingdom and the quantities and values were converted into United States units.] |