From the above-named date, however, and onwards, each succeeding and various power altered type, weight, or alloy, with more or less arbitrariness, but always to the increasing of the confusion of the system as a whole. And it was to remedy this confusion, or to reduce it somewhat, that the monetary union of the four electoral princes of the Rhine was established (8th June 1386), under the lead of the three towns, Frankfort, Speyer, and Worms; under which the four princes, Frederick, Archbishop of Cologne, Carl, Archbishop of Treves, Adolf, Archbishop of Mainz, and Rupert, Count Palatine of the Rhine, agreed upon a common minting of gold gulden. According to the treaty, 66 such gulden were to be minted from the Cologne mark of gold, each of the alloy of 22 carats 6 grs. gold, and 1 carat 6 grs. silver. In 1402 this coinage was confirmed at Mainz by the Mint edict of Rupert II.[4] Seven years later, 1409, the three spiritual electors, Frederick, Archbishop of Cologne, John, Archbishop of Mainz, and Werner, Archbishop of Treves, made a new and slightly different treaty, for the purpose of again reducing the alloy of the gulden from 22-1/2 to 22 carats. At this rate the system was, in the same year, at Speyer, formally accepted for themselves by the Netherlands, and at Cologne also, in 1409, by the Empire generally. The detailed and various changes which the independent princes and powers of Germany subsequently made, it is out of the question to follow. To instance only in brief. In 1419 Frederick of Brandenburg ordered the coining of gulden for his own states, at the rate of 64-1/2 to the Cologne mark, and of the fineness of 19 carats--a very considerable reduction in the metal value of the coin. In 1422, only three years later, Sigismund was coining gulden 66-1/2 to the mark and 22 carats 6 grs. fine--a value somewhat higher than that accepted for the empire in 1409. In 1428-29, accordingly, the Emperor Sigismund issued an imperial order, which was formally adopted by the Reichstag meeting at Eger (1437) and Nürnberg (1438), by which the Cologne mark was to be coined into 68 gulden and the fineness reduced to 19 carats. Four years later, 1442, the Emperor Frederick IV. projected a further reform and reduction, proposing to coin 72 pieces of 19 carats fine, but this was not carried into effect, probably as exaggerating the average depreciation of the content of the coin (or appreciation of the metal). The rate, therefore, established by Sigismund practically remained in force for a matter of sixty years. In the diet of 1495-97 (at Worms), however, a further slight reduction in weight and fineness took place, 69-1/3 pieces being struck out of the Cologne mark, and the fineness lowered to 18 carats 10 grs.