2. Alloys from which ornaments, vessels, statues, and coin were cast. Some of these contain lead, some zinc, and some are varieties of our brass. I shall designate these as cast metals or ornamental alloys. Those substances present in some quantity were evidently put in intentionally, and I have classed them as admixtures, while the unintentional ones in small quantities I have designated as impurities.
| WEAPON BRONZES. | |||
|---|---|---|---|
| Country. | Essential constituents. | Admixtures. | Impurities. |
| Egypt | Copper + 6 to 14 tin | .. | Iron. |
| Assyria | "+10 to 14 " | .. | .. |
| Greece | "+10 to 12 " | .. | Fe. Ni. Co. |
| Italy | "+11 to 16 " | Lead and Tin. | Ni. Fe. |
| Gaul | "+ 2 to 15 " | .. | .. |
| Britain | " + 7 to 14 " | 1 to 3 per. ct. lead. | Iron |
| Alps | " + 8 to 12 " | Trace to 1 p. c. lead. | Fe. Ni. |
| Bohemia | " + 5 to 11 " | .. | Fe. S. |
| N. Germany | " + 8 to 16 " | .. | Nickel. |
| Denmark | " + 6 to 12 " | To 1 p. c. zinc. | Ni. Co. |
| Russia | " + 9 to 16 " | Lead | Ni. |
| II.—CAST METAL FOR ORNAMENTS. | |||
| Country. | Essential constituents. | Admixtures. | Impurities. |
| Egypt | Copper + 4 to 11 tin | 7 to 17 lead. | Traces |
| Assyria | " +10 to 14 " | .. | Pb. Fe. Ni. |
| Greece | " + 6 to 12 " | Lead. | Fe. Ni. |
| Italy | " + 1 to 7 " | Zinc, lead. | Fe. Ni. |
| Gaul | " + 5 to 15 " | Lead | .. |
| Britain | " + 5 to 15 " | 2 p. c. lead. | Nickel. |
| Alps | " + 4 to 12 " | Zinc. | Pb. Fe. Ni. |
| Bohemia | " + 4 to 11 " | Lead. | .. |
| N. Germany | " + 6 to 17 " | Pb. rarely zn. | Ni. |
| Denmark | " + 5 to 12 " | 1 p. c. zn. | Fe. Ni. Co. |
| Russia | " + 7 to 16 " | Pb. zn. | Ni. |
The following general statements are based upon these tables:
We see that the peoples named forged their weapons and tools from very different alloys; pure copper at one extreme, bronze with 20 per cent. tin at the other. Experience had everywhere taught them that copper and bronzes poor in tin are too soft, while bronzes with an excess of tin could not be used for weapons and tools on account of being too brittle.
They had also learned that lead and zinc considerably lessened the strength and tenacity of weapon bronze, while small quantities of iron, nickel, and cobalt are, at least, not injurious. So all races, although we can prove that they tried very different mixtures, finally adopted very simple and tolerably constant alloys. The bronze weapons of all countries frequently contain from 6 to 16 per cent. of tin, but usually between 8 and 12, with slight contamination of iron and nickel. Few nations have allowed lead to be used, fewer yet some zinc.
For casting, the oldest races used the same kind of bronze as for weapons and tools. In many cases a few per cent. of lead were added to make the casting easier. The Romans used zinc in addition to lead in large quantity as a constituent of their alloys, and they made old bronze, bronze-brass, and brass. Afterward many nations of middle Europe used zinc alloys.
Small quantities of iron, nickel, and cobalt are found for well known reasons in nearly all bronzes as harmless impurities.
Traces of sulphur are also found in them. This injures the quality of the alloy, and discloses the fact that such bronzes were not made from pure oxide ores, but from those containing sulphur pyrites. At the time when such bronzes were produced the mines had probably reached a considerable depth.
Some of the weapon bronzes made by the ancients contain traces of phosphorus, an element as important in hard bronze as carbon is in steel.