ALUM, ALUM CAKE, PATENT ALUM, AND SULPHATE OF ALUMINA. Description and uses.-These names refer to various similar articles all of which contain sulphate of alumina as their essential ingredient. The different varieties or grades differ in the other ingredients present and may be classified as follows:

(1) Crystal alums, containing either potassium sulphate, ammonium sulphate, or sodium sulphate and water of crystallization (about 45 per cent) and not more than a few hundredths of 1 per cent of ferric oxide (iron oxide), and less than 15 per cent of oxide of aluminum (usually 10 to 12 per cent). They are usually made by dissolving refined hydrate of alumina in sulphuric acid, filtering, adding the sulphate of potassium, ammonium, or sodium, and crystallizing the alum. (2) Burnt alums, made from crystal alum by the elimination of most of the water. They contain more than 15 per cent of alumina. (3) Iron-free sulphate of alumina, containing from 16 to 22 per cent of oxide of alumina and not more than a few hundredths of 1 per cent of ferric oxide. This grade is usually made from refined hydrate of alumina, but also directly from bauxite by a secret process for the elimination of the iron always present in the crude mineral.

(4) Sulphate of alumina, containing from 16 to 22 per cent of oxide of alumina and from about 0.2 per cent of ferric oxide up to 0.75 per cent of ferric oxide. This grade is made directly from the crude mineral bauxite by solution in dilute sulphuric acid, followed by filtration from insoluble matter and evaporation. If the content of alumina is over 21 per cent, it is called "concentrated alum."

(5) Alum cake or aluminous cake contains less than 15 per cent of alumina, but rarely less than 14 per cent, and from about 0.2 per cent up to 0.75 per cent of ferric oxide, together with insoluble or earthy matter up to 10 per cent. It is made by the treatment of crude bauxite, or even clay, with strong sulphuric acid without any evaporation or attempt to eliminate insoluble matter. It is the lowest quality of all.

Patent alum is an obsolete term.

Alums are used largely in the preparation of sizing material in paper manufacture, as a mordant in dyeing, for the purification of water and sewage on a large scale, for tanning skins, for deodorizing mineral oils, and for hardening plaster casts. They are also used in the manufacture of color lakes, in medicine, and as an ingredient of some baking powders.

Production. In the United States these substances are produced on a large scale from bauxite. Most of that consumed is of domestic manufacture and many municipal and industrial waterworks produce their own sulphate, which is consumed by them and does not enter the market. The production of sulphate of alumina in the United States in 1916 was 153,860 short tons, valued at $4,410,741, of which 6,037 tons did not enter the market. In 1917 the total production was 178,738 short tons. In 1916 there were nine plants in the eastern United States producing alum of various grades with a total output for the year of 27,257 short tons, valued at $1,177,881. In 1917 there was a decrease in the production, the total being 19,714 short tons.

Imports have not been large and there has been a decrease since 1915. In 1914, 152,808 pounds of lump alum were imported, 92 per cent of which came from England. Imports of sulphate of alumina have averaged less than 1 per cent of the domestic production.

OTHER COMPOUNDS OF ALUMINA.

Description and uses.-Other compounds of alumina of commercial importance are the acetate, known as “red liquor," used as a mordant in calico dyeing and printing and in waterproofing and fireproofing fabrics; and aluminum chloride, used for refining mineral oils, for carbonizing wool, and in the manufacture of certain organic compounds.

Production. In 1914 three plants were reported to be manufacturing aluminum chloride with a total output for the year of 4,702 short tons, valued at $311,900.

INTERPRETATION AND COMMENTS.

In the tariff act of 1913 no distinction is made between the different grades of alum and sulphate of alumina on the market, but all are dutiable under the same ad valorem rate. In the act of 1909 these articles were divided into two classes carrying specific rates of onefourth cent per pound and three-eighths cent per pound, respectively. The lower rate was imposed on the products " containing not more than fifteen per centum of alumina and more than three-tenths of one per centum of iron oxide." If it is determined to impose specific duties on these products the revision of the specifications which distinguished between the different grades should be considered. The specification "more than three-tenths of one per centum of iron oxide " might well be changed to read "more than one-tenth of one per cent of ferric oxide," because the grades sold as "iron free" will always contain less than 0.1 per cent of ferric oxide, whereas the iron-containing grades commonly dealt with commercially will frequently contain less than 0.3 per cent of oxide of iron. It is suggested that the term "oxide of iron" should be replaced by "ferric oxide," because the latter has a precise chemical meaning, whereas the term "oxide of iron" is not definite, since there are two different oxides of iron, known as ferrous oxide and ferric oxide, containing different proportions of iron.

The term "patent alum" is obsolete and may well be omitted. The provision "alumina, hydrate of, or refined bauxite," might be changed to "aluminum hydroxide, or refined bauxite."

The largest use of ammonia in normal times is in the form of ammonium sulphate for fertilizer purposes. Liquid anhydrous ammonia is largely used for refrigeration, ammonium nitrate and ammonium picrate are used as explosives, aqua ammonia for household cleaning, and other ammonium compounds chiefly for chemical purposes.

The war developed a large domestic manufacture of synthetic nitric acid based on the production of ammonia for conversion into nitric

acid, Chilean nitrate failing to supply the quantities demanded for explosives. The ammonia necessary for this large volume of nitric acid came from by-product coke ovens, from the direct synthesis of ammonia from nitrogen of the air and hydrogen, and from calcium cyanamide made from calcium carbide and atmospheric nitrogen. Two Government synthetic nitrogen plants are located at Muscle Shoals, Ala. One plant, with a rated output of 30 tons of anhydrous ammonia per day, uses the method of direct synthesis of ammonia from nitrogen and hydrogen; the other plant, with a capacity of 22,000 tons of ammonia per year, uses the cyanamide process. These war developments give a potential ammonia capacity in excess of our normal needs.

CARBONATE OF AMMONIA.

Description and uses.-Commercial carbonate of ammonia, a mixture of ammonium carbonate and ammonium carbamate containing about 31 per cent of ammonia (NH,), is a white crystalline salt smelling strongly of ammonia, volatile when heated, and sometimes known as sal volatile. It is used in wool scouring, in some baking powders, smelling salts, and certain domestic cleaning powders.

Production. It is made by heating a mixture of sulphate of ammonia and chalk (calcium carbonate). The vapors of ammonia, carbon dioxide, and water, on cooling, condense to form the solid mixture of ammonium carbonate and ammonium carbamate. The crude product is usually purified by sublimation. The domestic output is unknown.

Imports prior to 1915 averaged about 370,000 pounds per annum, doubling in 1915, but declining to 76,160 pounds in 1918.

MURIATE OF AMMONIA.

Description and uses.-Muriate of ammonia or, correctly speaking, ammonium chloride, is ammonia combined with hydrochloric acid. It is also called sal ammoniac. The crude material is usually more or less dark colored, due to tarry impurities. Ammonium chloride comes in cakes (sal ammoniac), white and translucent, or in crystals (muriate of ammonia). It is used in pharmacy, in soldering, galvanizing iron, tinning, dyeing of textiles, and in electric dry batteries.

Production in 1914 was 11,511,934 pounds, valued at $641,040, supplying less than 60 per cent of domestic consumption. It can be made by treating aqua ammonia with hydrochloric acid, by distilling ammoniacal liquor and absorbing the ammonia gas in hydrochloric acid or by crystallization from a saturated solution of sulphate of ammonia and ordinary salt (sodium chloride).

Imports from 1910 until 1915 were between 9,000,000 and 14,000,000 pounds, decreasing until in 1918 only about 1,000,000 pounds were imported.

PHOSPHATE OF AMMONIA.

Description and uses.-There are two important phosphates of ammonia, the monammonium phosphate and the diammonium phosphate. These are of little commercial importance compared with the other ammonium compounds, but are used in the manufacture of fireproof cloth and paper and for medicinal purposes. The sodium salt of acid ammonium phosphate has important analytical uses. There is a fertilizer known as Ammo-Phos sold in two grades; one grade

contains 13 per cent ammonia and 47 per cent "available phosphoric acid," the other contains 20 per cent ammonia and 20 per cent "available phosphoric acid." This article is undoubtedly crude ammonium phosphates.

Production in this country is from calcium acid phosphate and ammonia, but the output is not known.

Imports decreased from a maximum of 68,039 pounds in 1911 to about 7,000 pounds in 1913, increasing sharply to 205,742 pounds in 1914, but declining to 1,000 pounds since 1915.

LIQUID ANHYDROUS AMMONIA.

Description and uses.-The term ammonia refers to a colorless gas composed of one part of nitrogen and three parts of hydrogen by volume. It is a weak alkali and has a strong, characteristic, pungent, penetrating odor. Under pressure it becomes a liquid which is then stored and shipped in steel cylinders, commonly containing about 100 pounds of ammonia. Liquid ammonia expands and vaporizes when the pressure is removed, and absorbs a large amount of heat, which give anhydrous ammonia its wide use for refrigeration and ice making.

Production in 1914 was 16,659,789 pounds, valued at $3,140,848. Imports are negligible, the largest being 2,698 pounds in 1918.

AMMONIACAL GAS LIQUOR.

Description and uses.-Ammoniacal gas liquor is the crude liquor obtained in the scrubbing and purification of the gasses evolved in the destructive distillation of coal and other organic nitrogenous substances. It is a pale-yellow to dark-brown liquid, smelling strongly of ammonia, hydrogen sulphide, and carbolic acid, and contains between 1 and 2 per cent of actual ammonia. For economy in transportation it is worked up into concentrated liquor, aqua ammonia, or some ammonium salt, usually sulphate of ammonia. The strength of ammonia is expressed in the number of ounces of pure sulphuric acid required to combine with the ammonia in 1 gallon of the liquor.

Production. Data for the total production are not available, although the Geological Survey reports the amount of ammoniacal gas liquor from by-product coke ovens.

Imports have been small and probably from Canada, transportation from abroad being economically impracticable.

INTERPRETATION AND COMMENTS.

The term ammonia refers to a colorless gas composed of one part of nitrogen and three parts of hydrogen by volume (NH). The word ammonium designates a chemical radical (NH) which does not occur by itself like ammonia, but is always in combination with some acid radical to form ammonium salts, such as ammonium sulphate. Ammonium is the correct scientific term and is the one in general use. "Muriate of ammonia is, correctly speaking, ammonium chloride. The advisability of changing the wording in paragraph 7 to correspond to this correct and generally used terminology should be considered. Should this be done, the classification in paragraph 7 would read as follows: "Ammonium carbonate, [rate]; ammonium chloride, [rate]; ammonium phosphate, [rate]; liquid anhydrous am

monia, [rate]; aqua ammonia, [rate]; and ammoniacal gas liquor, [rate]." (See par. 395.)

Description and uses.-Argols or crude tartar are a crystalline deposit which forms on the sides of wine casks during fermentation and contain about 50 to 85 per cent of acid potassium tartrate and 6 to 12 per cent of calcium tartrate. Wine lees are a similar deposit on the bottom of the casks and contain from 20 to 35 per cent of potassium acid tartrate and up to 20 per cent of calcium tartrate. Argols and wine lees (together with crude calcium tartrate referred to below) are the raw materials from which tartaric acid and all salts of tartaric acid, including cream of tartar, Rochelle salts, and tartar emetic, are prepared. Cream of tartar is refined potassium bitartrate, The better grades contain more than 99.5 per cent of potassium bitartrate and less than five parts per million of lead or other heavy metals. It is used principally as an ingredient in one variety of baking powder; in the dyeing and printing of textiles; in medicines and in food products, especially jellies, preserves, and beverages; in photographic developing and printing; in the deposition of silver on glass for mirrors and ornaments; and as a laboratory reagent. Rochelle salts or "tartrate of soda and potassa" is made from cream of tartar and soda ash, and is used in medicine, photography, and in chemical laboratories. Crude calcium tartrate is also a by-product of the wine industry and a raw material for the manufacture of tartaric acid.

Production.-Small quantities have been produced in the past by the wine industry and relatively insignificant amounts are now obtained from unfermented grape juice. Domestic production has probably never exceeded 1 per cent of the world's supply, and probably will be still further reduced as a result of the constitutional amendment prohibiting the manufacture and sale of intoxicating beverages. Although no reliable statistics of production are available, Italy and France are undoubtedly the chief sources of the raw materials of the tartar industry and together produce more than three-fifths of the world's supply. Spain, Portugal, and French Africa are also important producers. Austria-Hungary and Germany are minor sources of supply. In recent years Argentina has produced argols.

Imports of argols and wine lees containing not more than 90 per cent of potassium bitartrate for the fiscal years 1910-1918, inclusive, have averaged 28,670,615 pounds, valued at $3,416,326, and yielded an average revenue of $170,815.