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The approximate composition of all the five samples of gun-bronze was: copper, 88 per cent.; tin, 10 per cent.; and zinc, 2 per cent. The following table shows the results of tests on the hardness of the large bars:

Hardness of Aluminum-Bronze or Brass.

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The bars furnished by the government, and marked "navy bronze," were carefully cast at the New York Navy Yard, under the inspection of an officer detailed for that purpose, and were exceedingly fine castings. You will notice that they are of the composition of ordinary gun-bronze.

Two more bars of Cowles aluminum-bronze, cast in green sand, of the same grade as above, were officially tested for Lieutenant Martin E. Hall, U. S. N., at the Washington Navy Yard, with the

following results:

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PHYSICAL PROPERTIES OF SOME OF THE ALLOYS OF MANGANESE, COPPER AND ALUMINUM.

BY EUGENE H. COWLES, LOCKPORT, N. Y.

(Washington Meeting, February, 1890.) ·

THE German silver industry of the United States amounts in value to upwards of $6,000,000 or $8,000,000 annually. Several thousands of people earn a livelihood pursuing it, and the beautiful goods and articles manufactured from this time-honored and valued alloy are everywhere visible.

German silver enters largely into our street signs, harness and house hardware, and all manner of table-ware, solid or plated. There is scarcely an hour in the day that German or nickel-silver is not before our eyes.

The composition of this alloy is a very uncertain thing, and depends largely on the honesty of the manufacturer and the price the purchaser is willing to pay. It is composed of copper, zinc and nickel in varying proportions. The best varieties contain from 18 to 25 per cent. of nickel, and from 20 to 30 per cent. of zinc, the remainder being copper. The more expensive nickel-silver contains from 25 to 33 per cent. of nickel, and from 75 to 66 per cent. of copper. The nickel is used as a whitening element; it also strengthens the alloy and renders it harder and more non-corrodible than the brass made without it, of copper and zinc. Moreover, it reduces the odor emanating from brass, which is so disagreeable if it occurs about the dining-table.

Of all troublesome alloys to handle in the foundry or rollingmill, German silver is the worst. It is unmanageable and refractory at every step in its transition from the crude elements into rods, sheets or wire.

As a white-headed furnace-man recently said to the writer, in one of our large mills, "you can put eight crucibles into the fire, each containing exactly the same mixture of German silver, and when you take them out and pour them into slabs for rolling, seven will be a mass of scum or slag, or the stuff will swell up like rising bread and overflow the moulds, and be so full of blow-holes that it will look like a sponge. The eighth crucible will contain perfectly good metal. On remelting the next day, the bad stuff will, in nine chances out of ten, come out just as good metal as the eighth pot the day before, and under apparently the same conditions."

With nickel at seventy or eighty cents per pound, German silver

is necessarily an expensive metal, even in the ingot, and its extremely refractory nature makes it a still more costly luxury when fabricated into goods. With a view to obtain, if possible, a cheaper and better article than German silver, my brother, Alfred H. Cowles, and myself began some years ago to experiment with the alloys of copper and manganese. We found that while a pure metallic manganese could with difficulty be reduced by the ordinary methods, it could be cheaply reduced in the electric furnace. After a long course of experiments we have perfected a substitute for German silver, which is offered to the public by the Cowles Electric Smelting and Aluminum Co., under the name of "Silver-Bronze."

The genesis of this alloy is somewhat interesting. Of course, it was no new thing to bleach copper with manganese. Dr. Percy, the discoverer of aluminum-bronze, was also the discoverer or inventor of manganese-bronze. To him, and to him alone, is due the honor of having first made these two alloys.

Following his written description, several other makers have from time to time, within the past thirty years, attempted to produce a pure manganese-bronze, but without success. Some have even attempted its introduction into the German silver trade. But thus far it has been both too expensive to manufacture and too corrodible to permit a prolonged use.

In order to overcome the two prime difficulties, that of casting and that of corrosion, we have introduced a small percentage of aluminum into the alloy, with the happiest effect.

The successive steps that have been pursued are recorded in a list of upwards of two hundred distinct mixtures of the several metals, copper, zinc, tin, lead, aluminum, iron and manganese and the metalloid silicon, and experiments upon the same in ascertaining tensile strength, ductility, color, etc. The most important determinations derived from this list of experiments appear to be about as follows:

1. That pure metallic manganese exerts a bleaching effect upon copper more radical in its action even than nickel. In other words, we found that 18 per cent. of manganese present in copper produces as white a color in the resulting alloy as 25 per cent. of nickel would do, this being the amount of each required to remove the last trace of red.

2. That upwards of 20 or 25 per cent. of manganese may be added to copper without reducing its ductility, although doubling its tensile strength and changing its color.

3. That manganese, copper and zinc, when melted together and

poured into moulds, behave very much like the most "yeasty" German silver, producing an ingot which is a mass of blow-holes, and which swells up above the mould before cooling.

4. That the alloy of manganese and copper by itself is very easily oxidized.

5. That the addition of 1.25 per cent. of aluminum to a manganese-copper-alloy converts it from one of the most refractory of metals in the casting process into a metal of superior casting qualities, and the non-corrodibility of which must in many instances be far greater than that of either German or nickel silver.

The "silver-bronze" alloy especially designed for rods, sheets and wire has the following composition: Manganese, 18; aluminum, 1.20; silicon, 5; zinc, 13, and copper, 67.5 per cent. It has a tensile strength of about 57,000 pounds on small bars, and 20 per cent. elongation. It has been rolled into thin plate and drawn into wire .008 inch in diameter. A test of the electrical conductivity of this wire (of size No. 32) shows its resistance to be 41.44 times that of pure copper. This is far lower conductivity than that of German silver, and is a matter of considerable importance to electricians who may wish a cheaper and better material than can be had at present, from which to construct resistance-coils.

POSTSCRIPT.

The following letter, received since the foregoing paper was issued in pamphlet form, contains the final determination of the electrical characters of the silver-bronze alloy :

CASE SCHOOL OF APPLIED SCIENCE, CLEVELAND, Oн10, April 22, 1890. I have determined the resistance and change of resistance of The Cowles SilverBronze, as follows:

The resistance of one meter of the wire, one mm. in diameter, is 0.996 ohms. The change of resistance per degree centigrade is less than 0.00034 per cent. Its resistance is therefore about 52 times that of silver, about 48 times that of copper, and about 3.7 times that of German silver, and hence considerably greater than that of any other material known which is capable of being drawn into a strong, tough wire.

Its change of resistance for temperature is only about one-hundredth, at most, of that of German silver. My apparatus was only delicate enough to determine this as a superior limit. This makes its change of resistance for temperature far less than that of any known substance.

This metal is now known at the

HARRY FIELDING REID, PH.D.,

Professor of Physics, C. S. A. S. Brush works as "the metallic

insulator," and from our electrical standpoint is really a wonderful material.

WURTZILITE FROM THE UINTAH MOUNTAINS, UTAH.

BY WILLIAM P. BLAKE, NEW HAVEN, CONN.

(Washington Meeting, February, 1890.)

In addition to uintaite, the Uintah Mountains contain a deposit, or vein, of the peculiar hydrocarbon mineral, to which I have given the name wurtzilite,* in honor of the chemist, Henry Wurtz, Ph.D., of New York, who, in 1865, described grahamite, and who has added to our knowledge of the composition of the hydrocarbon minerals.

Wurtzilite and uintaite are very similar in appearance, but are very different in their physical and chemical properties. Both are black, splendent and shining in fresh fracture; but the wurtzilite has a decided toughness, and a degree of elasticity, especially when warmed, which suggests to some persons a resemblance to caoutchouc. It was at first, at Salt Lake, believed and reported to be a mineral form of India-rubber, and great expectations of its value as a substitute for crude rubber were indulged in. It was, however, found that it would not act like rubber with sulphur; it would not incorporate with it and become "vulcanized," and it was very refractory and insoluble in the ordinary solvents of rubber and of uintaite.

The elasticity, though unlike the elasticity of rubber, led to the reference of the mineral to the species elaterite, the only name under which an elastic bitumen is described in the mineralogies; and it is so called in the list of the mineral products of Utah, given in the last message of the Governor of the Territory.

The name elaterite, as used by Dana, covers at least three differing substances, ranging in specific gravity from 0.905 to 1.223. Two of the varieties are soft and elastic, much like India-rubber, and one is occasionally hard and brittle, imbedded in the softer kinds. All are rare, and comparatively unknown, and not generally represented in mineral collections. One of the varieties referred to here is the subterranean fungus from Derbyshire, described by Lister as early as 1673.

* Engineering and Mining Journal, xlviii., December 21, 1889,
VOL. XVIII.-32

p. 542..

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