Part 303

To blue copper or brass any one of the following recipes may be used:

I.—Dip the article in a solution of 2 ounces of liver of sulphur and 2 ounces of chlorate soda in 1,000 ounces of water.

II.—Dip the article in a solution of ferrocyanide of potassium very strongly acidulated with hydrochloric acid.

III.—Stir the article about constantly in a solution of liver of sulphur in 50 times its weight of water.

«Fusion Point of Metals.»—The point of fusion of common metals is as follows: Antimony, 808° F.; aluminum, 1,160° F.; bismuth, 517° F.; copper, 1,931° F.; gold, 1,913° F.; iron, 2,912° F.; lead, 850° F.; nickel, 2,642° F.; platinum, 3,225° F.; silver, 1,750° F.; tin, 551° F.; zinc, 812° F. Mercury, which is normally fluid, congeals at 38° below zero, F., this being its point of fusion.

«To Produce Fine Leaves of Metal.»—The metal plate is laid between parchment leaves and beaten out with hammers. Although films obtained in this manner reach a high degree of fineness, yet the mechanical production has its limit. If very fine films are desired the galvano-plastic precipitation is employed in the following manner:

A thin sheet of polished copper is entered in the bath and connected with the {474} electric conduit. The current precipitates gold on it. In order to loosen it, the gilt copper plate is placed in a solution of ferric chloride, which dissolves the copper and leaves the gold behind. In this manner gold leaf can be hammered out to almost incredible thinness.

«METAL FOIL.»

Tin foil is the most common foil used, being a combination of tin, lead, and copper, sometimes with properties of other metals.

I II III Per cent Per cent Per cent Tin 97.60 98.47 96.21 Copper 2.11 0.38 0.95 Lead 0.04 0.84 2.41 Iron 0.11 0.12 0.09 Nickel — — 0.30

I is a mirror foil; III is a tin foil.

Tin Foils for Capsules.—

I II Per cent Per cent Tin 20 22 Lead 80 77 Copper — 1

Tin Foils for Wrapping Cheese, etc.—

I II III Per cent Per cent Per cent Tin 97 90 92 Lead 2.5 7.8 7 Copper 0.5 0.2 1

Tin Foils, for Fine Wrapping, I and II; for Tea Boxes, III.—

I II III Per cent Per cent Per cent Tin 60 65 40 Lead 40 35 58.5 Copper — — 1.5

Imitation Gold Foils.—

Deep gold Pure gold Pale gold Per cent Per cent Per cent Copper 84.5 78 76 Zinc 15.5 22 14

Deep gold Deep gold Gold Per cent Per cent Per cent Copper 91 86 83 Zinc 9 14 17 dark pale reddish yellow yellow

Imitation Silver Foil.—Alloy of tin and zinc: harder than tin and softer than zinc: Zinc, 1 part; tin, 11 parts.

To Attach Gold Leaf Permanently.—Dissolve finely cut isinglass in a little water, with moderate heat, which must not be increased to a boil, and add as much nitric acid as has been used of the isinglass. The adhesive will not penetrate the cardboard or paper.

METH: See Mead.

METHEGLIN: See Mead.

METHYL SALICYLATE, TO DISTINGUISH FROM OIL OF WINTERGREEN: See Wintergreen.

METOL DEVELOPER: See Photography.

METRIC WEIGHTS: See Weights and Measures.

MICE POISON: See Rat Poison.