Seigniorage and the value of coins
Saturation point for coinage
1. When the number of coins issued is limited properly, a seigniorage charge does not reduce their money value; they are worth more as money than as bullion. The coinage thus far considered has been that of full-weight coins without seigniorage. The question now is, What is the effect of a seigniorage charge on the value of the coin as compared with the bullion that is in it? This is one of the most difficult phases of monetary theory. Two values must be thought of: one the value of the coin as money, the other the value of the bullion in it. When coinage is free and gratuitous, these two values are the same. How can they ever be different? The answer to the question is found in the theory of monopoly value. If the supply of coin is limited by the sole agency of issue, the value can be kept above the cost of production (i.e., in this case the bullion value), the seigniorage being the profit of the government. The limit within which the coinage must be kept is the number of coins that would circulate freely if they were made full weight without a seigniorage charge. This is the "saturation point" of the money demand of the country; it is a certain number of pieces of full-weight metal. If more than that amount gets into circulation it becomes worth less as money than as bullion, and it is melted or exported.
Example of seigniorage value in coins
If this full supply of money at a given moment is 100,000 pieces or dollars, a seigniorage charge of ten per cent. could be made if the number of pieces were not increased above 100,000. The government alone having the right of coinage, the need of money would give the circulating medium a monopoly value. The value of the money would rise until the coin would buy one ninth more bullion than was in it, but if there were any further rise the citizens would begin to take coins to the mint. After the ten per cent. charge was taken out they would receive a coin which, though containing one tenth less bullion, would be worth very nearly the same as the metal taken to the mint. No considerable depreciation could take place unless the volume of business fell off so that less money was needed than at the old standard. In that case there would be no outlet for the excess of coins until they fell to their bullion value, i.e., till they lost the entire value of the seigniorage, the monopoly element in them. Melting or exporting them before that point was reached would cause the loss of whatever element of seigniorage value they contained.
Example of excess and depreciation of coins
Assuming that the volume of business, or sum of exchanges, remains unchanged, let us consider what will result if the government begins to issue "on its own account." The number of coins might be increased until at the bullion price the total money value were equal to the original 100,000 full-weight coins, at which point exportation would take place. There being nine tenths as much precious metal as before, it would require ten ninths as many pieces, or 111,111 pieces, to have as great a value as the 100,000 had before. At this point there is no further profit to the government in issuing coins of that weight. To make a further profit it must again reduce the amount of pure metal in the coin.
Medieval examples of depreciation
This is essentially what occurred often throughout the Middle Ages. A ruler debased the quality or reduced the weight of money, but for a time the new coin, having the same money use, circulated as freely as the old coin. If, as so often happened, the ruler yielded to the temptation to issue more in order to get the profit, the older, heavier coins at once began to go abroad or into the melting-pot. Then occurred a fall in value, mystifying alike to the prince and the people. The reason is now perfectly plain: the number of pieces issued had not been kept within the proper limits, and the coins went down to their bullion value.
Difficulties with full-weight subsidiary coins