COURT AND TREASURY DECISIONS.

Bichromate of soda was held dutiable as a chemical compound and not by similitude as bichromate of potash under the act of 1883.Mason v. Robertson, 139 U. S., 624, reversing 29 Fed., 684, and overruling Biddle v. Hartranft, 29 Fed., 90.

Hydroxide of chromium in the state of its first production, unrefined and unfit for use for dyeing or tanning, without being subjected to refining processes, was held free of duty as an article in a crude state used in dyeing or tanning n. s. p. f., and not dutiable as a chemical compound under the acts of 1897 and 1909.-United States v. Continental Color & Chemical Co., 2 Ct. Cust. Appls., 165 (T. D. 31679), affirming G. A. 7132 (T. D. 31102).

Chromium fluorine was held dutiable as a chemical salt and not as a coal-tar color or dye under the act of 1890.-G. A. 1874 (T. D. 13602).

PRUSSIATES AND CYANIDES OF POTASH AND SODA.

SUMMARY.

Description. The prussiates of potash and soda are double salts of prussic acid, the other base material being iron. The ferrous iron salts (ferrocyanides) are the yellow prussiates, while the ferric iron salts (ferricyanides) are the red prussiates.

The prussiates are used for making Prussian blue and other blue colors; for calico printing and dyeing; ferricyanide is used as a part of the sensitive coating for "blue-print papers." Owing to the shutting off of potash salts from Germany, the sodium salts have almost entirely replaced the potash salts.

Potassium and sodium cyanide are both white salts of prussic acid and their properties are very similar. The cyanides are used for extracting precious metals from their ores by the "cyanide process"; for fumigating citrus fruits, raw imported cotton, grain elevators; for the bath in electroplating; and for the casehardening of iron.

Domestic production. The production of prussiates and cyanides of all kinds during 1914, as shown by the census of manufactures amounted to about 8,000 short tons. Confidential figures for 1917 on the soda salts alone show a considerable increase over the 1914 production. This increase has been due probably to the reduction of imports caused by the war.

Prior to the war our production did not supply our total consumption, as considerable quantities were imported.

Until recently the cyanides were made in this country chiefly from metallic sodium, ammonia, and coke by the Castner process, a singie firm controlling practically the entire production. During 1917 and 1918 there have been new processes developed (cyanamid and Bucher process) which will offer strong competition to the Castner process. The prussiates are then made from the cyanide.

Cyanides are produced chiefly at Perth Amboy, N. J. Manufacture of these products by the Bucher process had been started at Saltville, Va., but the plant has been taken over by the Government for nitrogen fixation. Potassium prussiates are also made at Niagara Falls, N. Y.

Foreign production. Figures on foreign production are not available. Manufacturers in this country report that their competition has been chiefly from Germany and England. Germany is undoubtedly the largest producer.

Imports. The imports of cyanides have been chiefly from Germany and England, with Germany furnishing a larger quantity. In 1915 the imports of potassium cyanide were chiefly from AustriaHungary and Canada and were probably reexported especially from Canada.

The imports are competitive with the domestic production.

Prices. The prices of prussiates and cyanide of potash have increased to 10 times the price prevailing prior to the war. Prussiate of soda prices increased to a maximum in 1916 of 15 times the prewar price and in 1917 the price was about 4 times the prewar prices. All these advances in prices are due to the shutting off of potash salts from Germany. Cyanide of soda was not listed prior to the war, but since potash salts could not be obtained from Germany, sodium salts have replaced them, so the price of cyanide of soda has increased 800 per cent from 1916 to 1918. The price of cyanide of soda dropped to 26 cents in July, 1919, and remained around that to the present time, due to small demand for the product and the competition of imports.

Tariff history. Prussiates of potash were dutiable under the acts of 1883 and 1890 at 10 cents per pound for the red, and 5 cents per pound for the yellow. The act of 1894 made both the red and yellow dutiable at 25 per cent ad valorem. Under the acts of 1897 and 1909 the red was dutiable at 8 cents per pound and the yellow at 4 cents. The act of 1913 reduced the duty to 2 and 11 cents per pound, respectively.

Prussiate of soda, yellow, was not mentioned specially until the act of 1909, which imposed a duty of 2 cents per pound. The act of 1913 reduced this duty to 3-cent per pound.

Cyanide of potash was first mentioned specifically in the act of 1897. This act and the act of 1909 imposed a duty of 12 per cent ad valorem. The act of 1913 piaced cyanide of potash on the free list.

Cyanide of soda was first mentioned specifically in the act of 1913 on the free list. Prior to the act of 1913 it was dutiable as cyanide of potash. (T. D. 22521).

GENERAL INFORMATION.

PRUSSIATES OF POTASH AND SODA.

Description and uses. The prussiates of potash and soda are double salts of prussic acid. The other base material besides potash or soda is either ferrous or ferric iron. The ferrous salts are yellow, while the ferric salts are a deep red color.

Yellow prussiate of potash is potassium ferrocyanide, K4Fe(CN)。. 3H,O.

Red prussiate of potash is potassium ferricyanide, K,Fe(CN). Yellow prussiate of soda is sodium ferrocyanide, Na,Fe(CN).. 10H2O.

Red prussiate of soda is sodium ferricyanide, Na,Fe(CN)..H2O. Potassium ferrocyanide, or yellow prussiate of potash, forms large orange-yellow crystals which do not change on exposure to the air, but they lose all of their water of crystallization on being heated to 100° C., at the same time they lose their color, being converted into a white powder. This chemical compound is largely used for making Prussian blue; in calico printing and dyeing; for the casehardening of iron; for making potassium cyanide and ferricyanide; and to a certain extent as a chemical reagent.

Potassium ferricyanide, or red prussiate of potash, crystallizes in deep red prism like crystals without water of crystallization. A

solution of the salt is intense yellow in color. When treated with ferrous iron salts it gives a blue pigment known as "Turnbull's Blue." An alkaline solution of potassium ferricyanide is a powerful oxidizing agent, and is used as such in calico printing for a "discharge" on indigo and other dyes. Potassium ferricyanide is also used as part of the sensitive coating for "blue-print papers.

Sodium ferrocyanide, or yellow prussiate of soda, crystallizes in large lemon-yellow crystals containing 10 molecules of water of crystallization. These crystals like yellow prussiate of potash lose all of their water of crystallization on heating to 100° C. In fact, sodium and potassium ferrocyanide are very similar in their properties, one salt can be substituted for the other in most cases. Owing to the shutting off of potash salts by the war the sodium salt has replaced the potassium ferrocyanide entirely. It is not likely potassium ferrocyanide or ferricyanide will again be used to the same extent as it was in the past.

Sodium ferricyanide, or red prussiate of soda, is known and crystallizes with one molecule of water. This salt, however, is not as common an article of commerce as are the other prussiates.

Preparation. The ferrocyanides or yellow prussiates were formerly made by fusing iron filings and nitrogenous animal materials of any kind (horn, blood, hair, wool waste, and leather scrap) with potassium or sodium carbonate depending on the salt which was desired. This method has been replaced by more modern and economical processes. It is known, however, that one firm in this country is using this old method to produce potassium ferrocyanide from scrap leather.

Ferrocyanides are now prepared from cyanogen gas (C2N2) and hydrocyanic gas (HCN) present in coal gas. These two gases are converted into ferrocyanides by two different methods. (1) The cyanogen and hydrocyanic acid are removed from the coal gas after the tar has been removed by "scrubbing" with a dilute solution of ferrous sulphate. These two products, along with some ammonia present in the gas, combine with ferrous sulphate, forming an insoluble salt of iron-ammonium-cyanide. This salt is then converted into calcium ferrocyanide by treating with lime. The calcium salt is then converted into a double ferrocyanide of potassium and calcium by means of potassium chloride. This salt is changed into potassium ferrocyanide by further treatment with potassium carbonate. The solution is filtered and the ferrocyanide of potash crystallized from the filtrate. (2) Ferrocyanide is also produced from coal gas during the process of purifying the gas from hydrogen sulphide. Iron oxide is used to remove the hydrogen sulphide from the gas, and at the same time the cyanogen and hydrocyanic acid combine with the iron oxide, and on exposure to the air oxidation to ferrocyanides takes place. The spent iron oxide from this process contains considerable ferrocyanide and is either recovered by the gas company or the spent oxide is sold to a chemical company who does the recovery.

Sodium ferrocyanide can be produced from the crude sodium cyanide produced by the Bucher process of nitrogen fixation. This process is at present (1918) being developed, and it has a very promising future. The crude cyanized briquettes produced in the process are treated with sufficient water to form a stiff paste. This paste is then steamed in an agitated vessel. The sodium cyanide and iron

in the briquettes react with the water to form sodium ferrocyanide, caustic soda, and hydrogen. The solution is filtered, and on cooling a fine quality of sodium ferrocyanide crystallizes out of the filtrate. With this process developed to a commercial scale, it will offer serious competition to the other methods of producing ferrocyanides.

The ferricyanides or red prussiates are prepared from the ferrocyanides by oxidation with chlorine gas. The ferrocyanides are usually treated with chlorine while dissolved in water. An excess of chlorine must be avoided. Other methods of preparation are mentioned, but this is the one usually employed. The ferricyanides are then crystallized from the solution in the same manner as the ferrocyanides.

Sodium ferrocyanide is also prepared by lixiviating sodium cyanide with hot water in the presence of iron, the sodium cyanide and iron combining chemically to form sodium ferrocyanide. This process is used to convert sodium cyanide prepared from cyanamid and by the Castner process into ferrocyanide.

CYANIDES OF POTASH AND SODA.

Description and uses.-The cyanides of potash and soda are described in the act of 1913 by the following language: Paragraph 580. Potash, cyanide of. (Free

Paragraph 605. Soda, cyanide of. (Free list.)

Potassium and sodium cyanide are both white salts of prussic acid, and their preparation and properties are very much alike; so they can be discussed together.

The cyanides are exceedingly poisonous when taken internally. When treated with an acid, they liberate prussic acid, or hydrocyanic acid, which is a very poisonous gas. The cyanides come into commerce as white lumps or powder and are very soluble in water. The salts smell like bitter-almond oil or crushed peach kernels, owing to the evolution of traces of prussic acid by the action of the carbon dioxide and moisture of the atmosphere.

Potassium cyanide contains, theoretically, 40 per cent of cyanogen (CN), which is the active constituent. The commercial product contains about 38 per cent of cyanogen. Sodium cyanide, owing to the lower molecular weight of sodium, contains 53 per cent of cyanogen, and consequently has a reactive value of 1.3 times that of cyanide of potash. Commercial grades of these two salts and mixtures of them are usually assayed as potassium cyanide. Therefore, mixtures containing considerable cyanide of soda will show on analysis over 100 per cent cyanide of potash. The commercial grades may assay as low as 65 per cent cyanide of potash, but 95 to 98 per cent is customary, and those products containing much sodium cyanide will, as pointed out, run over 100 per cent potassium cyanide.

The two biggest uses for sodium cyanide are the "cyanide process" of extracting precious metals from their ores, and fumigation. Sodium cyanide or hydrocyanic acid generated from the same is used for fumigating citrus fruits, raw cotton imported into the United States, railroad cars coming into this country from Mexico, grain elevators, and rooms. The property of a solution of cyanide to dissolve precious metals (gold and silver) gives sodium cyanide its large use in the mining industry. This same property gives cyanides their