Europe (especially Germany and the United Kingdom) was gradually switching at the time to the gold standard. But the members of the Latin Monetary Union paid no attention to its emergence. They printed ever increasing quantities of gold and silver coins, which constituted legal tender across the Union. Smaller denomination (token) silver coins, minted in limited quantity, were legal tender only in the issuing country (because they had a lower silver content than the Union coins).
The LMU had no single currency (akin to the euro). The national currencies of its member countries were at parity with each other. The cost of conversion was limited to an exchange commission of 1.25%.
Government offices and municipalities were obliged to accept up to 100 Francs of non-convertible and low intrinsic value tokens per transaction. People lined to convert low metal content silver coins (100 Francs per transaction each time) to buy higher metal content ones.
With the exception of the above-mentioned per capita coinage restriction, the LMU had no uniform money supply policies or management. The amount of money in circulation was determined by the markets. The central banks of the member countries pledged to freely convert gold and silver to coins and, thus, were forced to maintain a fixed exchange rate between the two metals (15 to 1) ignoring fluctuating market prices.
Even at its apex, the LMU was unable to move the world prices of these metals. When silver became overvalued, it was exported (at times smuggled) within the Union, in violation of its rules. The Union had to suspend silver convertibility and thus accept a humiliating de facto gold standard. Silver coins and tokens remained legal tender, though. The unprecedented financing needs of the Union members - a result of the First World War - delivered the coup de grace. The LMU was officially dismantled in 1926 - but expired long before that.
The LMU had a common currency but this did not guarantee its survival.
It lacked a common monetary policy monitored and enforced by a common
Central Bank - and these deficiencies proved fatal.
In 1867, twenty countries debated the introduction of a global currency in the International Monetary Conference. They decided to adopt the gold standard (already used by Britain and the USA) following a period of transition. They came up with an ingenious scheme. They selected three "hard" currencies, with equal gold content so as to render them interchangeable, as their legal tender. Regrettably for students of the dismal science, the plan came to naught.
Another failed experiment was the Scandinavian Monetary Union (SMU), formed by Sweden (1873), Denmark (1873) and Norway (1875). It was a by-now familiar scheme. All three recognized each others' gold coinage as well as token coins as legal tender. The daring innovation was to accept the members' banknotes (1900) as well.
As Scandinavian schemes go, this one worked too perfectly. No one wanted to convert one currency to another. Between 1905 and 1924, no exchange rates among the three currencies were available. When Norway became independent, the irate Swedes dismantled the moribund Union in an act of monetary tit-for-tat.
The SMU had an unofficial central bank with pooled reserves. It extended credit lines to each of the three member countries. As long as gold supply was limited, the Scandinavian Kronor held its ground. Then governments started to finance their deficits by dumping gold during World War I (and thus erode their debts by fostering inflation through a string of inane devaluations). In an unparalleled act of arbitrage, central banks then turned around and used the depreciated currencies to scoop up gold at official (cheap) rates.