Excerpt from Annual Report of the Director of the Mint to the Secretary of the Treasury for the Fiscal Year Ended June 30, 1891
Washington: Government Printing Office, 1891. Page 66. – Historical Reference Collection, United States Mint.
The regulations governing the mint service provide for special assays of current coinage of the mints, as follows:
SEC. 9. From the first and two subsequent deliveries in each week of gold and silver coins of each denomination of coin delivered by the coiner, specimen pieces, two in number, shall be taken, certified, and enclosed by the superintendent and assayer in the same manner as above prescribed for trial by the annual assay commission, when they shall be promptly forwarded to the Director of the Mint by registered mail for assay by the assayer of the Bureau of the Mint.
SEC. 10. The value of the special assay coins shall be returned at the end of each six months (June 30 and December 31) to the proper mints.
In order to enable the Director to know from day to day that the coins being issued at the mints conform in all respects to the requirements of law, a laboratory was established in 1878 on the fourth floor of the Treasury Department, which has proved a valuable adjunct to the Bureau.
Special examinations are also made in the laboratory, for the Treasury Department, of coins and other material for the purpose of detecting and preventing counterfeiting, and for custom requirements.
During the calendar year 1890 there were tested in the laboratory of this Bureau 196 gold coins and 1,010 silver coins, all of which were found to be within the legal requirements in regard to weight, fineness, and mechanical perfection.
Tables will be found in the appendix showing the fineness of the coins assayed and the percentage of coins of various degrees of fineness.
Compiled and transcribed by the United States Mint, Office of the Historian.