The pages below are from two different Scientific Americans published shortly after my 1892 U.S. Assay Office New York ingot #10, 8.93 ozs and melt #682 was produced at this very location.
First, from February 15, 1902, the cover photographs depict the assaying of both gold and silver at the New York Assay Office.
The #1 photograph is the weighing room, #2 melting gold bullion; #3 pressing the assay sample; #4 muffle furnaces for fire assay; #5 humid assay for silver; and #6 extracting the silver with boiling acid.
The article written to follow the cover above discusses the assaying process in great detail and notes that a follow up article is forthcoming that will discuss refining. To my surprise, I have been able to find that article as well.
Published on March 15, 1902, the follow up article describes the melting and refining processes. The #1 photograph is the stamping $8,000 gold bars with fineness, weight and value; #2 concentrating the silver solution and precipitating the silver; #3 separating the gold from the silver by boiling with Sulfuric acid; #4 stamping value, weight and fineness on silver bars; and #5 pressing precipitated silver into "cheeses".
The gentleman at the desk in the #1 photograph is identified as Mr. B. T. Martin, New York Assay Office Chief Melter and Refiner. The article says he worked there since 1850 and became Chief Melter and Refiner in 1883. This is awesome, just think, a photograph of the guy in charge when my 1892 U.S. Assay Office New York ingot #10, 8.93 ozs and melt #682 was produced. Maybe he stamped it sitting there at that very desk? Most likely he knew who AGB was! (the initials on the reverse)