Approximately 12,000 pounds of pure metal arrived too late in 1922 to escape duty and was placed in the warehouse. Parts of this quantity were sold late in 1922 and during 1923, but some remained in the warehouse. About two-thirds of the "imports for consumption" of metallic and scrap magnesium shown above consist of this material, and one-third of magnesium imported in 1923. The average value of the total quantity was 67 cents a pound, but according to one importer the price of imported ingot metal over 99 per cent pure ranged from 70 to 80 cents a pound plus a duty of 40 cents a pound.

Owing to the unsettled conditions in Germany, the chief or only foreign source of metallic magnesium, together with the duty on magnesium, there was little inducement to import magnesium except on definite orders. Speculative buying was too risky, and in this respect the tariff tended to stabilize the industry.

It is interesting to note that in spite of the tariff and the marked decline in imports, the average value of domestic ingot magnesium declined from $1.60 a pound in 1922 to $1.25 in 1923; and indications early in 1924 lead to the inference that the average value for this year will be near $1 a pound. The selling price is governed to a large degree by competition with foreign magnesium, but the reduction in price is made possible by improvement in technique of manufacturing, the installation of equipment for the production of semifinished structural forms in both pure metal and alloys, and progress in uses. The high first cost of magnesium, however, continues to be the principal difficulty in extending its use. As sales increase for uses where price is not a prime factor, further decreases in price may be expected and should promote other uses which thus far have not been commercially practicable.

DEVELOPMENT AND OUTLOOK 14

The largest use for magnesium continues to be the deoxidizing or desulphurizing of other metals, particularly nickel and Monel metal. This field of use is gradually broadening as the cost of magnesium decreases. Magnesium has also been used experimentally in the deoxidation and desulphurizing of copper, and a considerable quantity is used for scavenging low-grade scrap brass. It is also possible that small quantities of magnesium may improve the qualities of zinc in commercial form.

Magnesium is an essential constituent of high-strength aluminum alloys, the demand for which is rapidly increasing. The magnesium content of these alloys is usually about 0.5 per cent. Other alloys known as magnalium or magnalite consist of an aluminum base with 3 to 6 per cent of magnesium. The use of these alloys also promises to increase.

Although the domestic magnesium powder sold in 1923 came wholly from stocks previously accumulated, the consumption of foreign powder was considerable, and the demand for the powder is

14 Information relating to this subject and on the physical and chemical properties of magnesium and its alloys is contained in a book entitled "Magnesium," published by the American Magnesium Corporation. Niagara Falls, N. Y., in 1923 (177 pages, illustrated by half tones and text figures; price $2.50).

expected to improve gradually. As rapid ignition in flash powders is largely dependent on the relation of the bulk of magnesium powder to its weight, the recent placing on the market of a magnesium powder with 40 per cent more volume for a given weight than had been previously obtainable will tend to stimulate the use of flash powders and will better meet the needs of manufacturers of flare shells and tracer bullets.

Castings ranging from simple uncored pieces to complicated cored aircraft-motor parts can now be produced. The low specific gravity of magnesium and its property of burning at its melting point have been severe obstacles in the development of the process of casting, far greater than have been met in the casting of any other metal.

Finished products, which have been sold largely on an experimental basis, include aircraft-motor parts, including crank cases, oil pans, fuel-line fittings, pistons, special alloy bearings, and instrument cases; lens holders; field glasses; parts of moving-picture machines; surveying instruments; receivers and transmitters for radio sets; artificial limbs; motorcycle-engine parts; shuttles, bobbins, and spools for weaving machinery; rotating parts of air compressors and vacuum pumps; gasoline line and carbureter fittings; railway signal instrument parts; and balloon valve frames.

Magnesium sheet has been produced suitable for experimental development of the following uses: Moving parts of precision instruments, celluloid-covered drafting rulers, meter disks, scale pointers, chemical-balance parts, hydrofluoric-acid containers, dry-battery elements, speedometer parts, metal buttons, and portable drafting tables. The principal requirement in the production of satisfactory sheet metal is an ingot free from flaws, which in turn involves special melting and alloying equipment and careful regulation of temperature. The manufacture of extruded rod and tubing has proved simpler than that of other forms, as magnesium and several of its alloys flow readily at pressures and temperatures well within the limits of the extrusion equipment. In addition to this equipment special straightening machines are necessary for the production of marketable material. The products of single extrusions range from a series of eight wires each 0.03 inch in diameter to symmetrical sections of tubing with a maximum diameter of 18 inches. Products now being developed include control levers for aircraft, meter-disk spindles, knitting and crochet needles, tubular tennis-racket frames, fuel lines for aircraft, and tapered tubing for billiard cues.

Magnesium wire has been used principally in the development of vacuum bulbs for radio work. The wire is raised to its melting point inside the bulb and eliminates the last traces of oxygen and nitrogen by chemically combining with them.

One of the most promising developments is that of forging or hot pressing magnesium, as the metal becomes plastic and flows readily at temperatures well within the limits of commercial practice. After it has been sufficiently worked to destroy the cast grain texture, it assumes qualities that commend its consideration for pistons and connecting rods for internal-combustion engines, propellers and supercharger disks for aircraft, golf-club heads, and parts of machines where this process of form changing may supersede casting.

Strontium ore was mined in the United States in 1916, 1917, and 1918, but none has been mined since. The total quantity mined in the United States is less than 5,000 short tons. Most of this was obtained from deposits in California, but some was mined in Arizona, Texas, and Washington. Other workable deposits have been reported in Utah. All these deposits have been briefly described in the reports on strontium for 1916, 1918, and 1919. Most of the ore is celestite (strontium sulphate), but some in California and Washington is strontianite (strontium carbonate). Interference with commerce during the World War created a market for domestic ores that resulted in temporary activity in the mining of strontium ore in this country, but this activity ceased as soon as foreign trade was reestablished. The deposits, however, are still available should the demand again arise or the price increase sufficiently to enable the producers to put the ore on the market in competition with imported ore. The market at present is chiefly at or near the Atlantic seaboard.

IMPORTS

The quantity of crude strontium ore imported prior to 1923 can not be determined, because a separate report of it was not kept in the customs offices at ports of entry prior to September 22, 1922, when the new tariff went into effect. It is estimated that between 1,500 and 2,000 short tons of ore is imported annually. In 1923 nearly 1,680 short tons of strontium ore was imported, valued at more than $12,500 at foreign ports of shipment.

Strontianite and celestite imported into the United States in 1922 (last quarter only)

Year

and 1923

1922 (Sept. 22 to Dec. 31). 1923..

The high value of the material imported in 1922 ($80 a ton) implies that this ore was ground and not crude lump ore.

Statistical data prepared chiefly by Mrs. E. R. Phillips. Statistics of imports compiled by J. A. Dorsey from the records of the Bureau of Foreign and Domestic Commerce.

PRICES

The price obtainable for strontium ore that might be mined in the United States is controlled by the price of the imported product delivered at the Atlantic ports of entry, because the factories that use most of the ore are in the eastern part of the country. Domestic celestite sold in 1917, during the war, at about $22 a ton and strontianite at about $38, but the deposits could probably be worked at a profit at much lower prices. The price of imported strontium ore at foreign ports of shipment in 1923 was about $7.50 a ton. To this should be added the ocean transportation and delivery charges, making the estimated cost at the American seaboard about $9.50 a ton. There is no duty on strontium ore. Mining of domestic strontiumore deposits appears to be dependent on the development of a western market for strontium chemicals, such as would result from the use of strontium salts in the manufacture of beet sugar by a process in general use in certain parts of Europe.

KNOWN STRONTIUM DEPOSITS IN THE UNITED STATES

Manufacturing companies that use strontium ore may be interested to learn of domestic deposits which have been either mined or prospected and some of which are available for development. The following is a list of such deposits:

Strontium chemicals were manufactured in the United States in 1923 chiefly from celestite imported from England. Three plants made strontium chemicals from ore during the year. E. I. du Pont de Nemours & Co. produced the largest quantity of chemicals at their plant at Paulsboro, N. J. The other producers in 1923 were the Mallinckrodt Chemical Works, at St. Louis, Mo., and the PowersWeightman-Rosengarten Co., at Philadelphia, Pa. Strontium