3. _#Subsidiary and Minor Coins.#_--All coins of a lower denomination than $1 belong to one or the other of these two classes. There are three subsidiary coins, the fifty cent, the twenty-five cent, and the ten cent pieces. The three cent piece is no longer coined. All other coins are minor coins. The peculiarity of the subsidiary and minor coins is that they are, as compared with the standard coins (gold and silver dollars), of a greater value than the value of the metal they contain. The subsidiary coins are legal-tender to the amount of $10, the minor to the extent of twenty-five cents. By legal-tender is meant that the government has ordered that it must be received in payment of all debts and articles bought. Gold coin and the silver dollars and certificates are legal-tender to any amount. 4. _#Treasury Notes.#_--Under this head are included that form of money ordinarily known as "greenbacks," from the color of their backs. They were originally issued during the civil war, and are promissory notes on the part of the government, and as such constitute a portion of the debt of the government. They are paper, which of itself is of no value, and no coin is deposited in the Treasury which they represent, as in the case of the gold and silver certificates. They thus cost the government nothing, and, as they are made legal-tender, and paid out by the government, they were just so much clear gain to it. At first they were not redeemable, i.e., exchangeable for coin at the Treasury, but since 1879 they are, and are therefore just as valuable now as any other form of money, though formerly worth much less than their face value. One hundred million dollars in gold is kept on deposit in the Treasury for their redemption.