QUESTION: Why were gold and silver selected as the money metals?
Answer: BECAUSE THEY ARE SCARCE. By confining money to these two precious metals, it was believed by the financiers that the volume of real money would never get so large that they could not control it. The limitation of money to these two scarce metals was a practical limitation to the supply.
So matters stood throughout the world until the discovery of such vast quantities of gold in California frightened the financiers. They feared that so much gold would be added to the currency of the world that prices would go down, bonds would decrease in value, and that they, the financiers, would be unable to control the supply of real money.
Consequently, they hired able writers, like Chevalier and MacLarren, TO WRITE AGAINST GOLD, in the same way that THE MONEY KINGS HIRED DAVID A. WELLS AND EDWARD ATKINSON TO WRITE AGAINST SILVER, more than a century later.
Germany and Austria excluded gold from their mints (1857) and Belgium and Holland adopted the single silver standard.
QUESTION: What checked the demonetization of gold?
The discovery of the rich silver mines in Nevada, Colorado and other Western States. The financiers saw that there would soon be more silver than gold, and they went to work to have the scarcer metal made the standard of value, and the money of final payment.
QUESTION: What nation led the others in the demonetization of silver?