Easton's Bible Dictionary (1897)
Which is an alloy of copper and zinc, was not known till the thirteenth century. What is designated by this word in Scripture is properly copper (Deut. 8:9). It was used for fetters (Judg. 16:21; 2 Kings 25:7), for pieces of armour (1 Sam. 17:5, 6), for musical instruments (1 Chr. 15:19; 1 Cor. 13:1), and for money (Matt. 10:9). It is a symbol of insensibility and obstinacy in sin (Isa. 48:4; Jer. 6:28; Ezek. 22:18), and of strength (Ps. 107:16; Micah 4:13). The Macedonian empire is described as a kingdom of brass (Dan. 2:39).
The “mountains of brass” Zechariah (6:1) speaks of have been supposed to represent the immutable decrees of God. The serpent of brass was made by Moses at the command of God (Num. 21:4-9), and elevated on a pole, so that it might be seen by all the people when wounded by the bite of the serpents that were sent to them as a punishment for their murmurings against God and against Moses.
It was afterwards carried by the Jews into Canaan, and preserved by them till the time of Hezekiah, who caused it to be at length destroyed because it began to be viewed by the people with superstitious reverence (2 Kings 18:4). ) The brazen serpent is alluded to by our Lord in John 3:14, 15.
Smith's Bible Dictionary (1863)
” In most places of the Old Testament the correct translation would be copper, although it may sometimes possibly mean bronze a compound of copper and tin. Indeed a simple metal was obviously intended, as we see from (8:9; 33:25; Job 28) Copper was known at a very early period.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
BRASS, This compound metal was probably unknown in ancient times, but bronze, a mixture of tin and copper, may sometimes be referred to under this name. That which is called brass in most passages of the sacred writings was doubtless what we call copper. Gen 4:22; Deut 8:9. It was used for a variety of purposes about the temple, and also for fetters, Jud 16:21; 2 Kgs 25:7; armor, 1 Sam 17:5-6; and musical instruments. 1 Chr 15:19 ,1 Cor 13:1.
The words brass, brazen, etc., occurring under the words Armor, Altar, Book, etc., are used in conformity with the common English translation of the Bible, and not with technical accuracy.