UNIVER

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The "New Standard," for watch cases, etc. is 18 carats of fine gold, and 6 of alloy. No gold of inferior quality to 18 carats, or the "New Standard," can receive the Hall mark ; and gold of lower quality is generally described by its com mercial value.

The alloy may be entirely silver, which will give a green. color, or entirely copper for a red color, but the copper and silver are more usually mixed in the one alloy according to the taste and judgment of the jeweler.

The following alloys of gold are transcribed from the memoranda of the proportions employed by a practical jeweler of considerable experience. When it is otherwise expressed, it will be understood all these alloys are made with fine gold, fine silver, and fine copper, obtained direct from the refiners. And to insure the standard gold passing the test of the Hall, 3 or 4 grains additional of gold are usually added to every ounce.

First Group. Different kinds of gold that are finished by polishing, burnishing, etc., without necessarily requiring to be colored:

The gold of 22 carats fine is so little used, on account of its expense and greater softness, that it has been purposely

omitted.

Second Group. Colored golds: these all require to be submitted to the process of wet-coloring, which will be explained; they are

used in much smaller quantities, and require to be very exactly

proportioned.

Third Group. Gold solders: these are generally made from gold of the same quality and value as they are intended for, with a small addition of silver and copper, thus:

Dr. Hermstadt's imitation of gold, which is stated not only to resemble gold in color, but also in specific gravity and ductility, con

*By others, 4 grains of brass are added to the solder; it then fuses beautifully and is of good color. Zinc is sometimes added to other good solders to increase their fusibility, the zinc (or brass when used) should be added at the last moment, to lessen the volatilization of the zinc.

sists of 16 parts of platinum, 7 parts of copper, and 1 zinc, put in a crucible, covered with charcoal powder, and melted into a mass.

Gold alloyed with platinum is also rather elastic, but the platinum whitens the alloy more rapidly than silver.

LEAD appears to have been known in the earliest ages of the world. Its color is bluish white; it has much brilliancy, is remarkably flexible and soft, and leaves a black streak on paper: when handled it exhales a peculiar odor. It melts at about 612°, and by the united action of heat and air, is readily converted into an oxide. Its specific gravity, when pure, is 11.445; but the lead of commerce seldom exceeds 11.35.

LEAD is used in a state of comparative purity for roofs, cisterns, pipes, vessels for sulphuric acid, etc. Ships were sheathed with lead and with wood, from before the Christian era to 1450, after which wood was more commonly employed, and in 1790 to 1800 copper sheathing became general; of late years, lead with a little antimony has likewise been used, also an alloy of copper and zinc and galvanized sheet iron. The most important alloys of lead are those employed for printers' type, namely, about

3 lead, 1 antimony, for the smallest, hardest and most brittle types.

4 lead, 1 antimony, for small, hard, brittle types.

5 lead, 1 antimony, for types of medium size.

6 lead, 1 antimony, for large types.

7 lead, 1 antimony, for the largest and softest types.

In addition to lead and antimony, type-metal also contains from 4 to 8 per cent. of tin, and sometimes 1 to 2 per cent. of copper; but as old metal is always used with the new, the proportions are not exactly known.

Stereotype-plates are made of 20 parts of lead, 4 of antimony, and 1 of tin.

Baron Wetterstedt's patent sheathing for ships, consists of lead with from 2 to 8 per cent. of antimony; about 3 per cent. is the usual quantity. The alloy is rolled into sheets.

Similar alloys, and those of lead and tin in various preparations, are much used for emery wheels and grindingtools of various forms by the lapidary, engineer, and others. The latter also employs these readily-fused alloys for temporary bearings, guides, screw nuts, etc.

Organ pipes consist of lead alloyed with about half its quantity of tin to harden it. The mottled or crystalline appearance so much admired shows an abundance of tin.

Shot metal is said to consist of 40 lbs. of arsenic to one ton of lead.

In casting sheet-lead, the metal was poured from a swing. trough upon a long and nearly horizontal table covered with a thin layer of coarse damp sand, previously levelled with a metal rule or strike. The thickness of the fluid metal was determined by running the strike along the table before the lead cooled, the excess being thus swept into a spill-trough at the lower end of the table; but the sheetlead now more commonly used, is cast in a thick slab, and reduced between laminating rollers; it is known as “milled lead."

The metal for organ-pipes is prepared by allowing the metal to escape through the slit in a trough, as it is slid along a horizontal table, so as to leave a trail of metal behind it; the thickness of the metal is regulated by the width of the slit through which it runs, and the rapidity of the traverse; a piece of cloth or ticken is stretched upon the casting table. The metal is planed to thickness, bent up and soldered into the pipes.

Lead pipes are cast as hollow cylinders and drawn out upon triblets; they are also cast of indefinite length without drawing. A patent was taken out for casting a sheath of tin within the lead, but it has been abandoned.

Lead shot are cast by letting the metal run through a narrow slit, into a species of colander at the top of a lofty tower; the metal escapes in drops, which for the most part assume the spherical form before they reach the tank of water into which they fall at the foot of the tower, and this prevents their being bruised. The more lofty the tower, the larger the shot that can be produced; the good and the bad shot are separated by throwing small quantities at a time upon a smooth board nearly horizontal, which is slightly wriggled; the true or round shot run to the bottom, the imperfect ones stop by the way, and are thrown aside to be re-melted; the shot are afterwards riddled or sifted for size, and churned in a barrel with black lead.

MERCURY is a brilliant white metal, having much of the color of silver, whence the terms hydrargyrum, argentum vivum, and quicksilver. It has been known from very remote ages. It is liquid at all common temperatures; solid and malleable at 40° F., and contracts considerably at the moment of congelation. It boils and becomes vapor at about 670°. Its specific gravity at 60° is 13.5. In the solid state its density exceeds 14. The specific gravity of murcurial vapor

is 6.976.

MERCURY is used in the fluid state for a variety of philosophical instruments, and for pressure gages for steam-engines, etc. It is sometimes, although rarely, employed for rendering alloys more fusible; it is used with tin-foil for

silvering looking-glasses, and it has been employed as a substitute for water in hardening steel. Mercury forms amalgams with bismuth, copper, gold, lead, palladium, silver, tin, and zinc.

Mercury is commonly used for the extraction of gold and silver from their ores by amalgamation, and also in watergilding.

NICKEL is a white brilliant metal, which acts upon the magnetic needle, and is itself capable of becoming a magnet. Its magnetism is more feeble than that of iron, and vanishes at a heat somewhat below redness, 630°. It is ductile and malleable. Its specific gravity varies from 8.27 to 8.40 when fused, and after hammering, from 8.69 to 9.00. It is not oxidized by exposure to air at common temperatures, but when heated in the air it acquires various tints like steel; at a red-heat it becomes coated by a gray oxide.

NICKEL is scarcely used in the simple state, but principally used together with copper and zinc, in alloys that are rendered the harder and whiter the more nickel they contain; they are known under the names of albata, British plate, electrum, German silver, pakfong, teutanag, etc.: the proportions differ much according to price; thus the

Commonest are 3 to 4 parts nickel, 20 copper, and 16

are 5 to 6 parts nickel, 20 copper, and 8

About two-thirds of this metal is used for articles resembling plated goods, and some of which are also plated; the remainder is employed for harness, furniture, drawing and mathematical instruments, spectacles, the tongues for accordions, and numerous other small works.

The white copper of the Chinese, which is the same as the German silver of the present day, is composed of 31.6 parts of nickel, 40.4 of copper, 25.4 of zinc, and 2.6 of iron, 17.48 13.0

53.39

The white copper manufactured at Sutil in the duchy of Saxe Hildburghausen, is said by Keferstein to consist of copper 88.000, nickel 8.753, sulphur with a little antimony 0.750, silex, clay, and iron 1.75. The iron is considered to be accidentally introduced into these several alloys along with the nickel, and a minute quantity is not prejudicial.

Iron and steel have been alloyed with nickel; the former (the same as the meteoric iron which always contains nicke!) is little disposed to rust: whereas the alloy of steel with nickel is worse in that respect than steel not alloyed.

PALLADIUM is of a dull-white color, malleable and ductile. specific gravity is about 11.3, or 11.86 when laminated.