Calamine brass a mixture of the virtually indistinguishable zinc ores smithsonite and hemimorphite) as the zinc component of brass. The resulting brasses, produced by heating a mixture of copper and calamine to a high temperature for several hours (allowing zinc vapor to distill from the ores and permeate the metallic copper), contained a significant amount of slag material resulting from the non-zinc components of calamine. The use of ore rather than metallic zinc also made it difficult to accurately produce the desired final proportion of copper to zinc. This process is known as cementation. Calamine brass was produced using proportions of two-sevenths
Francis Metallic Surfboat Francis Metallic Surfboat The Francis Metallic Surfboat is a boat, currently housed at 130 West Center Street in Douglas, Michigan. It was listed on the National Register of Historic Places in 2015. It is one of two known surviving examples of its kind, one of the first type of coastal rescue craft used. The Francis Metallic Surfboat was designed by Joseph Francis, an inventor who specialized in inventing and constructing maritime lifesaving equipment. Francis constructed 137 of these vessels from about 1849 to 1857, of which 48 were used on the Great Lakes. This particular boat dates from approximately 1854,