Part 36

«FILE ALLOYS.»—Many copper-tin alloys are employed for the making of files which, in distinction from the steel files, are designated composition files. Such alloys have the following compositions:

«Geneva Composition Files.»—

I II Copper 64.4 62 Tin 18.0 20 Zinc 10.0 10 Lead 7.6 8

«Vogel’s Composition Files.»—

III IV V Copper 57.0 61.5 73.0 Tin 28.5 31.0 19.0 Zinc 78.0 — 8.0 Lead 7.0 8.5 8.0

VI.—Another alloy for composition files is copper, 8 parts; tin, 2; zinc, 1, and lead, 1—fused under a cover of borax.

«EASILY FUSIBLE OR PLASTIC ALLOYS.»

(These have a fusing point usually below 300° F.)

(See also Solders.)

I. Rose’s Alloy.—Bismuth, 2 parts; lead, 1 part; tin, 1 part. Melting point, 200° F.

II. Darcet Alloy.—This is composed of 8 parts of bismuth, 5 of lead, and 3 of tin. It melts at 176° F. To impart greater fusibility, 1⁠/⁠16 part of mercury is added; the fusing is then lowered to 149° F.

III.—Newton alloy melts at 212° F., and is composed of 5 parts of bismuth, 2 of lead, and 3 of tin.

IV.—Wood’s Metal.—

Tin 2 parts Lead 4 parts Bismuth 5 to 8 parts

This silvery, fine-grained alloy fuses between 151° and 162° F., and is excellently adapted to soldering.

V.—Bismuth, 7 parts; lead, 6 parts; cadmium, 1 part. Melting point, 180° F.

VI.—Bismuth, 7 to 8 parts; lead, 4; tin, 2; cadmium, 1 to 2. Melting point, 149° to 160° F.

«Other easily fusible alloys:»

VII VIII IX Lead 1 2 3 Tin 1 2 3 Bismuth 1 1 1 Melting Point 258° F. 283° 311°

«Fusible Alloys for Electric Installations.»—These alloys are employed in electric installations as current interrupters. Serving as conductors on a short length of circuit, they melt as soon as the current becomes too strong. Following is the composition of some of these alloys.

────+───────────+──────+─────+─────────+──────── │ Fusing │ │ │ │ │temperature│ Lead │ Tin │ Bismuth │Cadmium ────+───────────+──────+─────+─────────+──────── I │ 203° F. │ 250 │ 500 │ 500 │ — II │ 193° F. │ 397 │ — │ 532 │ 71 III │ 168° F. │ 344 │ 94 │ 500 │ 62 IV │ 153° F. │ 260 │ 148 │ 522 │ 70 V │ 150° F. │ 249 │ 142 │ 501 │ 108 VI │ 145° F. │ 267 │ 136 │ 500 │ 100 ────+───────────+──────+─────+─────────+────────

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These alloys are prepared by melting the lead in a stearine bath and adding successively, and during the cooling, first, the cadmium; second, the bismuth; third, the tin. It is absolutely necessary to proceed in this manner, since these metals fuse at temperatures ranging from 850° F. (for lead), to 551° F. (for tin).

«Fusible Safety Alloys for Steam Boilers.»—

───────+───────+────+────+────────+──────── │ │ │ │ Melting│ Atmos. │Bismuth│Lead│Zinc│ point │pressure ───────+───────+────+────+────────+──────── I. │ 8 │ 5 │ 3 │ 212° F.│ 1 II. │ 8 │ 8 │ 4 │ 235° F.│ 1.5 III. │ 8 │ 8 │ 3 │ 253° F.│ 2 IV. │ 8 │ 10 │ 8 │ 266° F.│ 2.5 V. │ 8 │ 12 │ 8 │ 270° F.│ 3 VI. │ 8 │ 16 │ 14 │ 280° F.│ 3.5 VII. │ 8 │ 16 │ 12 │ 285° F.│ 4 VIII. │ 8 │ 22 │ 24 │ 309° F.│ 5 IX. │ 8 │ 32 │ 36 │ 320° F.│ 6 X. │ 8 │ 32 │ 28 │ 330° F.│ 7 XI. │ 8 │ 30 │ 24 │ 340° F.│ 8 ───────+───────+────+────+────────+────────

«Lipowitz Metal.»—This amalgam is prepared as follows: Melt in a dish, cadmium, 3 parts, by weight; tin, 4 parts; bismuth, 15 parts; and lead, 8 parts, adding to the alloy, while still in fusion, 2 parts of quicksilver previously heated to about 212° F. The amalgamation proceeds easily and smoothly. The liquid mass in the dish, which should be taken from the fire immediately upon the introduction of the mercury, is stirred until the contents solidify. While Lipowitz alloy softens already at 140° F. and fuses perfectly at 158°, the amalgam has a still lower fusing point, which lies around 143 3⁠/⁠5° F.

This amalgam is excellently adapted for the production of impressions of various objects of nature, direct impressions of leaves, and other delicate parts of plants having been made with its aid which, in point of sharpness, are equal to the best plaster casts and have a very pleasing appearance. The amalgam has a silver-white color and a fine gloss. It is perfectly constant to atmospheric influences. This amalgam has also been used with good success for the making of small statuettes and busts, which are hollow and can be readily gilt or bronzed by electro-deposition. The production of small statues is successfully carried out by making a hollow gypsum mold of the articles to be cast and heating the mold evenly to about 140° F. A corresponding quantity of the molten amalgam is then poured in and the mold moved rapidly to and fro, so that the alloy is thrown against the sides all over. The shaking should be continued until it is certain that the amalgam has solidified. When the mold has cooled off it is taken apart and the seams removed by means of a sharp knife. If the operation is carried on correctly, a chasing of the cast mass becomes unnecessary, since the alloy fills out the finest depressions of the mold with the greatest sharpness.

«Amalgam for Plaster.»—Tin, 1 part; bismuth, 1 part; mercury, 1 part. Melt the bismuth and the tin together, and when the two metals are in fusion add the mercury while stirring. For use, rub up the amalgam with a little white of egg and brush like a varnish on the plaster articles.