In the year 107AD, the Emperor Trajan attempted to revitalize the money suppy ordering that all the old coinage be “melted down all the worn-out coinage” according to the historian Casssius Dio. In essence, the treasury was greatly depleted due to his prolonged campaign to conquer Dacia, modern day Yugoslavia region.
Trajan actually demonitzed all silver and gold coinage that had been issued prior to the reign of Nero and his monetary reform of 64AD, which was the first step in the debasement. Therefore, Trajan was recalling all old “worn” coinage and reissuing it with at a lower standard of his period.
At the time of Trajan, the finances of the Empire were is crisis. The fineness of the silver denarius when he came to power in 98AD was 93.5%. In 100AD, Trajan lowered the fineness to 92.75%. As the cost of the Dacian war escalated, he again reduced the fineness to in 103AD to 91.5% This would decline further reaching 90% in 112AD.
Consequently, Trajan demonetized the old coinage which was of a heavier silver standard meaning they were no longer valid payment for taxes. This forced people to return them in exchange for new denarii. The old were then melted and in effect this increased the money supply by about 10%.