The coinage law of 1873 authorized the unlimited coinage of a silver coin, known as the "trade dollar," which it was supposed might be used as a substitute for the Mexican dollar in our trade with the Orient. It was legal tender in the United States only to the amount of $5. It contained 420 grains of standard silver, and so was slightly heavier than the standard silver dollar (412 1/2 grains), and was worth a trifle more than the gold dollar. Owing, however, to the decline in the gold price of silver, it became profitable to convert silver bullion into these trade dollars. In 1876 they were deprived of their legal tender quality and their coinage was restricted. In 1878 further coinage was prohibited except for "proof pieces," and in 1887 provision was made for the redemption of the outstanding coins at par in standard silver dollars or subsidiary silver. The total issue of trade dollars was $35,965,924, of which $7,689,036 were presented for redemption.