preventable loss may easily be saved by bringing average practice up to best practice.

In foundry practice it is easy to catch the zinc oxide from the present form of melting furnace, but unless petroleum or gas is used as fuel the oxide caught is so mixed with foreign material as to be worthless, except possibly for making zinc chloride for impregnating timber.

ALUMINUM.

The consumption of aluminum in the United States in 1914 was the largest on record and amounted to 79,129,000 pounds, valued at $14,523,000. Sixty years ago aluminum was a chemical curiosity, valued at $90 per pound. The total amount produced in 1883 was 83 pounds. About 1889 it was selling in the United States at $4.50 per pound, and the output was 75 pounds per day. With cheapened electric power and improvements in manufacturing processes, due to the genius of men like Charles M. Hall, the metal has ceased to be a "chemical" and its uses and applications are growing. At the end of 1914 it was selling at 19 cents a pound, but now, owing to the great demand, it is worth 35 to 37 cents a pound.

The consumption of metallic aluminum in the United States is much greater than the output and, though some metal is exported, a much larger quantity is imported. Much secondary aluminum is recovered from one source or another, largely from scraps, borings, and turnings. This recovered aluminum amounted, in 1914, to 6,253 short tons, or 12,506,000 pounds. The consumption of the metal is growing rapidly and the facilities for turning out enough for home consumption are inadequate. The one concern manufacturing the metal in the United States has steadily expanded its plant capacity in recent years, and has recently acquired an immense plant capable of generating 100,000 horsepower at Whitney, N. C., financed by French capital, but on which work had been suspended.

The great increase in the consumption of metallic aluminum has been determined by the peculiar properties of the metal, especially its lightness. Commercial aluminum has a specific gravity of about 2.7, whereas the specific gravity of brass is about 3 times as great, that of steel about 2.8 times as great, and that of copper approximately 3.3 times as great. Hence the metal has been in demand in the manufacture of automobiles, aeroplanes, and dirigible balloons.

Aluminum vessels are coming into use in the brewing industry, varnish manufacture, the preparation of foodstuffs, the soap and candle industry, the refining of sugar and fatty and vegetable acids, and in the manufacture of high explosives, because of its ability to withstand the action, either separately or combined, of sulphuric and nitric acid.

Aluminum can be said to have no substitute, but is growing in importance as a substitute for copper for conducting electricity, and also as a substitute for tin in certain applications. When one considers the multiplicity of uses to which aluminum is now applied and the part that it is destined to play, the question of the domestic supply of bauxite, the mineral from which the metal aluminum is now made, assumes importance.

Bauxite. The domestic production of bauxite, the mineral from which all our metallic aluminum is now obtained, was over 219,000 long tons, valued at slightly over $1,000,000, in 1914, the largest on record. The imports were nearly 25,000 long tons. Our total consumption of the ore, therefore, was 244,000 long tons, of which the imports were slightly more than 10 per cent. These imports come from France, which is the most important producer. The United States ranks second, and of late years has rapidly gained on France.

Productive bauxite areas are confined exclusively to the Southern States, Arkansas, Tennessee, Georgia, and Alabama. The State of Arkansas has for many years produced more than 80 per cent of the bauxite mined in this country. The remainder comes from northwest and central Georgia, northeast Alabama, northeast and southeast Tennessee. It is reasonably certain that as time goes on more of this important mineral will be found in east Tennessee, as well as in north and central Georgia.

Bauxite has other uses than as the ore of aluminum: (1) as the base of salts, of which the alums, including aluminum sulphate, are the most important, aluminum sulphate, commonly referred to as “commercial alum," being used widely in the purification and clarification of municipal water supplies; (2) in the manufacture of alumina, or bauxite brick; (3) in the manufacture of artificial abrasives, one being alundun, which may be termed artificial corundum.

There are at present no substitutes for bauxite for use in making aluminum, although the preparation of potash sulphates from alunite deposits in Utah may result in the production of important quantities of alumina in such pure form that it will be available without further treatment. Another prospective source of alumina is ordinary clay, but although experiments have been in progress some years no process for obtaining alumina from clay has yet reached the commercial state. As common clay contains 10 to 39 per cent alumina the development of a commercial process warrants all the attention that can be given it.

So far as our present resources are concerned, we may consider the United States as practically independent, especially as new bauxite occurrences may be found, and American inventive genius may be trusted to solve the problem of extracting the metal from clay or some other alumina compound.

The plant required for manufacture of metallic aluminum is extensive and costly, so that at present this country is dependent on foreign sources for a part of its supply of metal. The new plant in North Carolina will help matters somewhat, but aluminum plants can not be built in a day, and they require large electric-power installations,

MANGANESE.

Manganese is one of those elements of vital importance to the basic industries of the United States which probably can not be completely supplied from domestic sources under present commercial conditions. Prior to 1870 iron found its principal use as wrought iron and crucible steel in which manganese is not used. The development of the Bessemer process about 1870 created a demand for manganese alloys, and manganese now constitutes about one-half of 1 per cent of all Bessemer and open-hearth steel. Manganese also forms a large part of some special alloys used in the manufacture of grinding and crushing machinery that are highly important in modern industries. Several chromium alloys may be substituted for manganese in such machinery, but the supply of readily accessible chromium ores in the United States is also deficient.

Manganese deposits have been worked in a number of States, notably Virginia, Georgia, Arkansas, Colorado, and California, the production in 1880 being 5,760 tons, valued at $52,000, and in 1913, 4,050 tons, valued at $40,000. The average production since 1880 has been 11, 000 tons a year and the average importation since 1890 has been 164,000 tons a year, which has been derived almost entirely from India, Brazil, and Russia. In addition to the imports of manganese ore, large tonnages of the alloys, ferromanganese and the lowergrade spiegeleisen, have been imported, averaging 71,000 tons and 36,000 tons a year, respectively, for the 14 years, 1901-1914, inclusive. The sources of these alloys are not recorded in detail, but until recently England appears to have supplied practically all of the imports.

In addition to deposits of manganese ore proper, deposits of lowergrade manganiferous iron ores are now exploited in several States, notably New Jersey, Virginia, Arkansas, Michigan, Minnesota, and Colorado. Spiegeleisen is made from a part of these.

There is no doubt that a higher price, which would be caused by the elimination of several sources of imports, would stimulate production from domestic mines, but it is doubtful whether extraordinarily high prices would bring forth a regular production of more than 20,000 to 25,000 tons of manganese ore a year. For only three years has the domestic production exceeded 25,000 tons a year. With higher prices the tendency would be toward greater use of

the manganiferous iron ores, of which there are large deposits, but ferromanganese has largely displaced the older product, spiegeleisen, which is made from the low-grade ores, so that a readjustment in processes would have to take place.

In 1898 it was estimated that the probable yield of the Russian deposits would be 80,000,000 tons, sufficient at the present rate of production to last about 80 years. In 1908 it was estimated that the better grades of ores in the known Indian deposits would probably last 30 to 40 years. No accurate estimate has been or probably can be made for the Brazilian deposits, but it may be said that they are enormous, and as yet are almost untouched. Considering the wide distribution of manganese deposits in general and certain relations of the deposits, there is reason for assuming that there remain in the tropical belts of Africa and South America undiscovered deposits of manganese ores that will be important sources of supply in the future. A number of important deposits are now known in these regions that can not be worked on account of lack of transportation facilities.

In contrast with most foreign ores, practically all of those in the United States must be washed, and in this process the losses of fine ore are high. These losses can be overcome, but the prices paid for the product do not warrant the increased expense. There are losses in the slag and dust in the blast furnace, as well as by volatilization, which range from 15 to 30 per cent. Unfortunately the losses are greater when the electric furnace is used.

A review of the American industry for the period of 14 years, 1901-1914, shows that out of the total manganese as ores and metal needed by all industries, most of which are fundamental and can not consider a substitute, only about 8 per cent has been derived from the various domestic sources. It would seem that there is an excellent opportunity for United States capital to develop the Brazilian deposits, if for no other reason than to be in a position to furnish that Republic with the necessary supply of iron and steel for the railways which it will require in developing its agricultural resources and the exploitation of its vast forests.

CHROMIUM.

Although the salts of chromium have many minor uses, the metal finds its greatest use as an alloy with iron in the manufacture of high-grade steel for the most part uniquely adapted to special uses. Tool steel containing small amounts of chromium and tungsten permits a rate of cutting not possible with any other alloys and is therefore important in modern machine-shop practice.

The mineral chromite, which is the source of all salts and alloys of chromium, has been mined in Maryland, Pennsylvania, North Carolina, and California. The average production of chromite for the 13 years, 1901-1913, has been 250 tons per year, whereas for the same period the imports have averaged 39,000 tons each year. In addition large quantities of chromium alloys and salts are imported. There are important deposits of chromite in Rhodesia, New Caledonia, Russia, and Turkey, and the American imports come principally from Rhodesia and Turkey.

As deposits of chromite are usually irregular and of uncertain extent little ore is developed in advance of mining, and it is impossible to foretell either the early exhaustion of a deposit or the discovery of new deposits. Thus, although for some years the Turkish deposits were the most important source, their production is now greatly exceeded by that of Rhodesia. A slight increase in price might stimulate the domestic production of chromite, but there is great doubt whether the present demand can be supplied from the known deposits in the United States. If foreign ore were unobtainable much larger quantities would be mined in this country, especially in California.

THE RARER METALS.

Many of the minor or rarer metals, although showing only a small tonnage or money value when compared to the huge output of iron, copper, etc., have a greatly disproportionate importance in their relations to the industries of the country, human comfort, or even the destruction of human life, and although none of them are indispensable, their lack would in some directions cause the wheels of progress to turn backward for a short space.

A very important group of the rarer metals, known as the steelalloying metals, includes chromium, cobalt, nickel, tungsten, vanadium, and of less importance, molybdenum and titanium. By the use of these metals wonderful alloy steels containing six or seven metals have been evolved, the "high speed" steels, by the use of which one man now does as much work with metal-cutting machinery as could formerly be done by five men, as shown in fig. 3.

These alloy steels have been largely though not wholly developed in the United States. The tremendous quantity of special steel ordered in this country by the warring nations has shown the extreme importance of the steel-alloying metals and prices have increased by leaps and bounds.

The alloy tool steels are now sold as high as $2 and $3 a pound as compared with 50 to 60 cents a pound formerly, and meet no competition from the fine carbon tool steels formerly used. For carbon