For fire-extinguishing purposes there are other chemical extinguishers which may be used as substitutes for the carbon tetrachloride extinguishers in certain cases. They are not as suitable for use against electrical fires as the carbon tetrachloride, and are injurious to clothes.

Carbon tetrachloride-Imports for consumption-Revenue,

1911.

1915.

1916.

1917.

1918.

1919.

1920.

1912.

1913.

1914.

1915.

1916.

1917.

1918.

1919.

1920.

Carbon tetrachloride-Prices, wholesale (cents per pound), spot, New York.

[Oil Paint and Drug Reporter.]

Rates of duty, specific and ad valorem.

1 cent per pound.

CHLOROFORM.

[Par. 19, act of 1913, 2 cents per pound.]

SUMMARY.

Description.-Chloroform or trichlormethane is a colorless liquid having a characteristic ethereal odor. The vapors of chloroform when inhaled produce anesthesia; it is this property that gives chloroform its largest use. About 1 per cent of grain alcohol is usually added to chloroform to prevent its decomposition. It is also used as a solvent, as an antiseptic, and in denistry and medicine. Domestic production. The production of chloroform increased from 616,670 pounds, valued at $165,604, in 1904, to 1,869,685 pounds, valued at $477,538, in 1909. In 1914 the production had decreased over 500,000 pounds. This decrease may be attributed to the greater use of ether instead of chloroform. Our domestic production has supplied our consumption.

In 1909 New York produced 90 per cent of our total output. Chloroform may be manufactured from three different raw materials—carbon tetrachloride, acetone, and grain alcohol. The use of carbon tetrachloride was stimulated by the war demands for

acetone.

Imports. The imports of chloroform have been insignificant. The maximum of 2,444 pounds being imported in 1914.

Price. The price of chloroform at the beginning of 1918 was about three times the normal prewar price.

Tariff history.-Chloroform has carried a specific duty, which by the act of 1883 was 50 cents per pound. This duty has since been gradually reduced to the duty existing under the act of 1913, paragraph 19, 2 cents per pound.

GENERAL INFORMATION.

Description.-Chloroform or trichlormethane is a chemical compound of the formula CHCl,. The former is the name used exclusively in commerce. It is a clear colorless liquid of a characteristic ethereal odor and burning, sweetish taste. The Pharmacopoeia describes it as follows: "A liquid consisting of not less than 99 per cent nor more than 99.4 per cent by weight of CHCI,, and not less than 0.6 per cent nor more than 1 per cent of alcohol." A good grade should be colorless, have a specific gravity of 1.476 at 25° C., and should boil between 61 and 63° C. For anesthetic purposes it should leave no residue on evaporation, should be neutral to test paper, and should give no indication of hydrochloric acid when tested with silver nitrate.

The liquid itself is noninflammable but its vapors can be made to burn. The vapors of chloroform, when inhaled, produce anesthesia; it is this property that gives chloroform its largest use. Specially

purified grades of chloroform come into commerce with the additional designations according to the method of purification. The common ones are Anschutz, purified by distillation from salicylchloroform; and Pictet, purified by freezing.

Chloroform is an important solvent. It dissolves fats, resins, india rubber, sulphur, phosphorus, iodine, alkaloids, and many other organic compounds.

Air and sunlight are liable to cause the slow decomposition of chloroform with the formation of hydrochloric acid, chlorine, and sometimes carbonylchloride. It has been found that ethyl alcohol prevents this decomposition and therefore the addition of about 1 per cent is largely practiced. Thorpe states that carefully purified sulphur will also prevent this decomposition of chloroform.

Raw materials.-Chloroform is manufactured from three different raw materials-carbon tetrachloride, acetone, and grain alcohol. At the present time carbon tetrachloride is probably used more than the other two raw materials. (See Carbon Tetrachloride page 30.) Owing to the direct war demand on acetone, which caused an acute shortage of this material, it is likely that nearly all of the chloroform made during the war was manufactured from carbon tetrachloride. It is doubtful, however, if this abandonment of acetone as a raw material will be a permanent one. The war caused a great increase in the production of acetone and now that the war demand has disappeared it is quite likely that the price of acetone will be low enough to encourage its consumption in the manufacture of chloroform.

The use of grain alcohol in the manufacture of chloroform does not seem to be as prevalent as in the past.

All the carbon tetrachloride used in the manufacture of chloroform is made in this country. In normal times acetone and alcohol are produced in sufficient quantities in the United States for the manufacture of chloroform and the imports of these materials are small compared with quantity manufactured in this country. It would then appear that the manufacturers in this country are independent of foreign countries for their supply of raw materials for the manufacture of chloroform.

Process of manufacture.--(a) From carbon tetrachloride: The production of chloroform from carbon tetrachloride consists in the reduction of the carbon tetrachloride to chloroform by the means of nascent hydrogen, which is generated in the carbon tetrachloride. The conversion of the carbon tetrachloride to chloroform proceeds very slowly, and the mixture must be kept in constant agitation for a long period of time. When the carbon tetrachloride has been changed into chloroform, the chloroform is distilled from the retort, condensed, and subjected to purification as described below.

(b) From alcohol and acetone: A paper read before the American Institute of Chemical Engineers by Mr. F. W. Frerichs on the manufacture of chloroform from bleaching powder and ethyl alcohol gives the following method of procedure: Ethyl alcohol is diluted to 20 per cent in an iron still. A solution of bleaching powder containing 35 grams per liter is added slowly to the solution of alcohol, which has previously been brought to boiling. The alcohol and bleaching powder react at once to form chloroform, which passes out of the still and is condensed. In actual operation the manufacture

of 100 pounds of chloroform required 1,022 pounds of 35 per cent bleaching powder and 11.53 gallons of 94 per cent alcohol.

Acetone may be used in the above process or chloroform may be made from acetone by the action of chlorine itself instead of the bleaching powder.

For technical uses the chloroform produced by either of the above methods is usually purified by washing first with water, then with sulphuric acid, followed by a redistillation. For anesthetic purposes, where a very pure product is required, the chloroform is usually dried with calcium chloride before it is redistilled. The portion distilling over up to 64° C. is taken as pure chloroform. Other methods of purification are: Pictet's, which consists in separating the chloroform from the impurities by freezing, and Anschutz, which combines the chloroform with salicylic acid and gently heats the salicylchloroform, thus liberating pure chloroform which is condensed.

Besides the above methods of manufacturing chloroform and the subsequent purification of the product there may be mentioned the method of preparing chloroform from chloral by one distillation. One hundred parts of water-free chloral are treated with 300 parts of caustic soda of 1.1 specific gravity. The resulting chloroform is distilled from the mixture and needs no further purification. This method is used to some extent in preparing chloroform for anesthetic purposes, but it has no industrial application.

The manufacture of chloroform requires besides the raw materials considerable steam for distillation purposes and a small amount of power for agitation. Skilled labor is not required in the production, although careful chemical control is required.

Important uses.-1. Anesthetic purposes, which is the largest use. 2. Solvent for resins, fats, gums, sulphur, phosphorous, iodine, alkaloids, and many other organic compounds.

3. Antiseptic.

4. Medicinal purposes, colic, asthma, spasms, quinsy, hysteria, and scarlet fever.

5. Dentistry.

Substitutes and rival commodities.--For anesthetic purposes the chief rival of chloroform is ether. The production of chloroform in 1914 was 535,731 pounds less than in 1909, while the production of ether increased 953,457 pounds during the same period. As there was not an increase in the imports of chloroform but a decrease during these years, it is evident that ether has been replacing chloroform to a marked extent.

Chloroform—Prices, wholesale (cents per pound), spot, New York.

Chloroform in small cylindrical glass vessels 2 by inch, sealed on one end, with a small, thin glass bulb to prevent evaporation, was held by the classification committee at New York, May 8, 1918, to be dutiable at 25 per cent ad valorem under paragraph 17 of the act of 1913 as a medicinal substance in ampoules and not as chloroform under paragraph 19.