By using four types of metal, specific frequency resonance is suppressed.

Rust is gradually eating into the metal parts.

Lightning is liable to hit metal.

Copper and silver are both metals.

Iron is a useful metal.

Iron is a metal with many uses.

Iron is the most useful metal.

Instead of giving the money, that is the normal coin of the realm, which is the phrase that everyone used then, they would give them a token, and this token might be metal, might be wood, might be cardboard.

In other cultures, the balls were filled with earth, grain, bits and pieces of plants, and sometimes even pieces of metal.

Acid eats into metal.

Acids act on metals.

Acids act on many things including metals.

Acid acts on things which contain metal.

Acid acts on metals.

The acid ate into the metal.

The value of the coins depended on the weight of the metal used.

Metal contracts when cooled.

The acid burned the metal.

Gold is more precious than any other metal.

Hey, rust is eating away the metal.