The number and variety of commodities which at various times have served as standards are great. Various kinds of grain, rice, cattle, salt, tobacco, skins of animals, cacao, and various metals, of which the most important are lead, iron, copper, silver, and gold, may be mentioned. Of these, gold has best stood the various tests, and is now the standard in all the great commercial nations. Since commerce has been playing an important role in the affairs of nations, silver has been its only competitor. These two metals are better fitted for the work of a standard in all the respects we have mentioned than any of the other commodities. On account of their durability, divisibility, adaptability to the coiner's art, and high value, they are preeminently fitted for service as a medium of exchange, and their great beauty and consequent adaptability to purposes of ornamentation made them objects of universal desire very early in the history of civilization. Custom and law have also long favoured them. The victory of gold over silver in comparatively recent times is due chiefly to its superior value and its consequent extended use in international exchanges and in the payment of balances between banks. Legislation has also favoured it, but largely for this reason. It is, equally as good as silver in all other respects, and much better in this very important one.

Of secondary standards history presents us with numerous examples. During the years 1790-1796 France had such a standard in the depreciated government notes which displaced all other forms of money and which were issued by the Revolutionary governments as a means of meeting the extraordinary expenses of the time. During the years 1793-1821 the notes of the Bank of England, not being redeemable on demand in coin, depreciated and became a secondary standard. So comparatively slight was the depreciation of the notes during the greater part of the period, and so gradual their introduction as a secondary standard, that many people believed them to constitute the primary standard, and a number of theories in support of this contention gained currency. During our Revolutionary and Civil wars depreciated government notes came into general circulation as money and served as secondary standards. Italy, Greece, and Spain have such standards at the present time. In all of these instances silver or gold continued as the primary standard, and prices were commonly quoted in these metals as well as in the depreciated paper. The history of units of value is too complicated and in many cases too obscure to warrant any extended account here. The English pound sterling has probably had the longest continuous history of any of the units of value employed by modern nations. It dates back at least to the later Saxon period, and probably still farther. The name pound, however, has been the only really permanent element. For many centuries it consisted of silver, but the amounts which it represented were repeatedly diminished until from a pound's weight it ultimately fell to a few ounces. It was not represented in the form of a coin until modern times. In 1816 it was changed to gold and has remained unaltered to the present day. In France the same system of reckoning as in England, with the French names livre, sou, and denier instead of pound, shilling, and penny, was employed until 1795, when the modern franc was adopted as the unit. As in England, the amounts of metal represented by these names constantly diminished, and they were even less frequently represented in coins. In Germany the same system with the names pfund, schilling, and pfennig was originally employed, but a number of independent and widely different systems were developed in the free cities and independent principalities of the Middle Ages, and it was not until 1873 that the mark, consisting of .398247 of a gramme of gold, became the unit of the whole German Empire. In the United States the dollar has been the name of the unit since colonial times. Up to the establishment of our own coinage system it meant the Spanish milled dollar, but the act of 1792 defined it in terms both of silver and of gold, the ratio between the two being reckoned as 15 to 1. Its content in pure gold at that time was fixed at 24 3/4 grains, but in 1834 it was diminished to 23.22 grains, and has remained unchanged since that date.

It is by no means necessary that the unit should be represented in a coin, although it is desirable, as we have shown, that some coins should be made from the standard commodity. For example, though gold is the standard of value in this country and our unit, the dollar, is defined in the statutes as 23.22 grains of pure gold, we do not coin a gold dollar as its representative for the reason that it would be too small for convenient use. Our dollar coin is, therefore, made of silver. The same is true of the present French and German units. While the franc and the mark are both defined as a certain number of grains of gold, the coins designated by these names are, for convenience sake, made of silver. The English pound sterling, being a very large unit, is represented in a gold coin called the sovereign, which is of convenient weight and size for purposes of general circulation.