quality, is found in irregular masses, disconnected and imbedded in the country rock, and varying in weight from a few pounds to several hundred tons. Since this discovery, the mining and shipping of chrome ore from Placer county is becoming an important industry. Shipments are made from Auburn regularly, the ore coming from points on the Forest Hill and Georgetown divides; a great deal also is being shipped from Colfax, being brought over from what is known as Brimstone plains, a few miles above Iowa Hill. Smiley Bros. are the principal shippers from the latter point. Chrome deposits not yet opened are known to exist in other places in the county."

Character of ores.-The character of chrome ore is practically the same whatever the source, although it varies in the amount of chromium oxide contained, between 40 and 50 per cent. Its composition may be expressed by the formula Cr2O,FeO; but part of the chromium may be replaced by iron, or the iron may be partly replaced by magnesium. Aluminum is also sometimes present, and silica often accompanies the sand ore as an impurity.

Amount mined.-About 2,500 net tons were obtained from California during 1882. The price paid in Baltimore is $40 per ton, with slight variations according to percentage of chromium oxide.

Utilization.-All the chrome iron ore used in the United States at present is made into potassium bichromate by Messrs. Jesse Tyson & Sons, Baltimore, with the exception of a very small quantity of sand ore which is used in making chrome steel at the Brooklyn Chrome Steel Works. The amount so used does not exceed 1 per cent. of the chrome ore mined. Bichromate of potassium is, then, the one salt of chromium from which all the others are obtained. The wholesale price of bichromate in 1882 was 153 cents per pound. By far the greatest proportion of this salt is used in calico printing; the bichromate being dissolved in water and then deposited on the cloth in the desired color by suitable reagents. It is also made into the pigments chrome yellow and chrome green. A small quantity is used in electric batteries. Besides the bichromate made in Baltimore about 35 per cent. of the whole amount used is imported from Scotland, under a duty of 3 cents per pound. In 1882 the amount imported was 1,972,221 pounds. Formerly American chrome ore was exported to England, but latterly the English supply has come from Russia.

No chrome ore in any quantity has thus far been worked up outside of Baltimore; but about two years ago Messrs. Harrison Bros., of Philadelphia, established a branch of their color works, called the Kalion Works, where they have undertaken the decomposition of chrome ore, and it is believed they are still continuing the work.

Baltimore has for a long time enjoyed a monopoly in the manufacture of bichromate, not, however, without many efforts on the part of manufacturers in other cities to obtain a footing in the trade. In the past eleven years no less than fifteen attempts have been made to establish

works for decomposing chrome ore in other cities, particularly in Philadelphia, New York, and Boston.(a) Not only thousands, but tens and even hundreds of thousands of dollars have been thrown away in these attempts to accomplish what is put down in the text books as a compar atively simple operation. Factories have been built, and arrangements made for grinding and decomposing the ore, but in very few cases has the experiment lasted long enough to result in the production of a single pound of bichromate. It is an extremely difficult matter to carry on this manufacture so well as to produce bichromate at 15 cents per pound. But by long experience and methods of decomposition known only to themselves, Messrs. Tyson & Sons have been able to maintain a successful business and to compete with the two other manufactories in Scotland and France.

a There has been some talk of establishing works for the manufacture of bichromate in California; but, as has been pointed out by Mr. H. G. Hanks, the State mineralogist, the necessity of importing potash would be a most serious obstacle to commercial success, while the substitution of other alkalies (such as soda or lime) is not cousidered practicable.-A. W., jr.

TUNGSTEN.

BY DAVID T. DAY.

Sources.-The element tungsten has the general characteristics of a metal, but it is also capable of acting as a non-metallic element and can form an acid-tungstic acid. It is in this role that it is always found in nature, as the tungstic acid salt of iron, manganese, calcium, or lead. These tungstates are rare. The most abundant is wolfram, a mixture of tungstates of iron and manganese in varying proportions. The tungstate of iron may replace the manganese almost entirely, when the mineral receives the name ferberite; or the manganese may replace all the iron, giving the mineral hübnerite. Besides these, scheelite, the tung. state of calcium; scheelitine, tungstate of lead; and wolfram ocher, the anhydrous acid itself, are found in small quantities. Wolfram is found in the United States at Charles Lake's mine, Munroe, Connecticut; at Trumbull, in the same State; and at Blue Hill bay, Maine, on Camdage farm. Although the deposits are never very extensive, an attempt has been made to work the mines in these localities, but the ore has not proved rich enough, and at present no wolfram is mined in the United States. Wolfram also occurs at the Flowe mine, in Mecklenburg county, North Carolina; in Missouri near Mine la Motte, in Saint Francis county, near the Saint Francis river; and in the Mammoth mining district, Nevada.

Value.-Wolfram usually contains from 35 to 55 per cent. tungstic acid, and is worth about 10 cents per pound, or $80 to $100 per ton, in Germany. It is subject to an import duty of 20 per cent. ad valorem. The price has been rising slowly during the past year or two, not however from any marked increase in the demand. Metallic tungsten is worth 60 to 80 cents per pound in Liverpool.

Utilization.-Tungsten holds a peculiarly uncertain position from an industrial standpoint. It has been recommended for use in many widely different industries; but thus far it has not gained extensive application, principally for two reasons: it has proved either too expensive or it has failed to yield the advantages claimed for it in particular cases. Under the former may be mentioned the projected scheme of saturating inflammable fabrics with a solution of tungstate of soda to render them proof against fire; but experiments have usually drifted off to alum or some other cheap substance. Tungstate of soda is one of the many substances proposed for the prevention of boiler incrustations. Soluble tungstates are used to a limited extent in calico printing. By far the most important application of tungsten that has ever been proposed is in the manufacture of steel for certain special purposes. An extended

treatise on this subject will be found in the work by J. S. Jeans, (a) of which the following is a summary.

It was shown by the Duc de Luynes, in 1844, that a feature in the socalled damask steel was that it contained tungsten. Later, in 1860, F. A. Bernoulli made a series of experiments at the Royal Iron Foundry, in Berlin, on the alloys of iron and tungsten, which led him to the following conclusions: 1. By mixing tungstic oxide with turnings of gray cast iron and fusing them, the tungsten is reduced to the metallic state and cast steel is formed. 2. The carbon of the cast iron, and particularly that portion which is mechanically mixed with the iron, is consumed in reducing the oxide of tungsten, and metallic tungsten appears partly to take the place of the carbon in the steel.

There has been much dispute as to the real advantage of this replace. ment of carbon by tungsten. Mayer of Loeben, Styria, is assigned the credit of having first applied tungsten to the manufacture of steel on the large scale, and owing to the success which he attained tungsten steel has been declared to be of the highest quality in respect to fineness of grain, uniformity of structure, hardness, toughness, strength, and durability; but numerous adverse opinions have followed the experiments of others. Tungsten, like carbon, appears to diminish the ductility of iron; though by melting tungsten and iron it is possible to obtain steel much harder than with carbon alone, without the danger of incuring at the same time an excessive fragility when cold or difficulties of working while hot.

For uses which require an especial degree of hardness, a steel rich in tungsten, called "special" steel, is frequently employed. Thus a fine Sheffield steel for lathe tools contained, according to an analysis made in the laboratory of the Stockholm School of Mines, 9.3 per cent. of tungsteu, 0.7 per cent. silicon, and only 0.6 per cent. carbon. This steel, which is used without being tempered for turning cylinders of cast iron, is of sufficient hardness to scratch glass and yet is not fragile, for great difficulty is experienced in breaking a 3-inch bar.

The hardness communicated to iron by turgsten is not increased by tempering. Steel rich in tungsten cannot be hardened without breaking. It can only be worked cold by grinding, on account of its excessive hardness; by working hot with caution the desired form may be given to it, but steel rich in tungsten must be managed with great care to prevent its cracking, and it must be treated several times in succession before the desired form is attained. After the form is obtained by hammering hot, the steel should be hammered with quick light blows nearly cold before it is allowed to cool gradually.

In order to produce tungsten steel it is necessary in the first place to rid the wolfram of the impurities which it contains. According to Jacob it must in the first place be roasted, then treated by diluted acid, and finally washed with water; in this manner the sulphur and arsenic are

a"Steel, its History, Manufacture, and Uses," London, 1880.

eliminated. After being dried the residuum is raised to a strong heat in crucibles lined with damp charcoal, the tungstic acid is reduced to the metallic state, and a compound is formed containing iron and manganese. The product thus obtained is of a dark color and great density. From 5 to 25 per cent. is added to the steel, according to the proportion of tungsten desired.

To produce Bessemer steel containing tungsten Le Guen adds to the molten metal, when the operation is finished, some pig containing tungsten, also in the liquid state. This pig is prepared from a mixture of 90 per cent. wolfram and 10 per cent. of lime with tar. According to Le Guen, the tungsten increases the hardness of the metal, and up to a certain point its tenacity also. If, on the other hand, the proportion of tungsten becomes rather high, the strength diminishes.

Mushet has obtained a patent for producing tungsten steel by mixing finely pulverized wolfram with an equal weight of melted pitch, after which the mixture is run out on a dry stone slab, and is added in certain proportions to crucible steel. Mushet's "special" steel made in this way is remarkable for its hardness and strength. This class of steel is manufactured in Germany at the works of Wund & Co., at Buckaw, near Magdeburg, in Prussia; and in Hanover at Uslar on Solling. The magnets used at Siemens' telegraphic works in Berlin are also said to be made at Moabit of this steel. Its qualities are very different from those of ordinary steel, as although when annealed it is so hard as to resist the best files, it becomes soft when chilled, and presents an exterior full of cracks, for which reasons it must not be hardened. At a red heat it is malleable and is easily worked, but all tools made of it must be brought into shape by the hammer at once, and finished if necessary under the grindstone, as the file will not touch it afterwards. Tools of tungsten steel in use for planing and other machines at the Engine Works of Knoevenagel, in Hanover, are reported to stand longer than those made of the best Sheffield cast steel.

A species of steel invented by H. A. Levallois, of Paris, has been patented in England. This is said to be an alloy containing tungsten and nickel in various proportions, and it is claimed to be less liable to oxidize or rust than ordinary steel.

C. W. L. Bierman, of Hanover, manufactures alloys of cast iron and steel containing from 20 to 50 per cent. of tungsten, and from 1 to 6 per cent. of manganese, in ingots, which are sold for mixing with (and so introducing any desired percentage of tungsten into) iron or steel.

Experiments with tungsten steel have been made at Park's works, and at several establishments in Pittsburgh, but as yet it has not assumed industrial proportions in the United States. It does not seem probable that it will become a rival of chrome steel.

28 M R