These are made from soft iron and thinned out to delicate proportions. These are very, very early hinges.
Snipe hinges (also known as cotter pin, or staple hinges), are the simplest and probably the earliest hinges used on American furniture. See instructions with a diagram on how they are installed.

We make lots of nickel hardware. Want more? We can provide any of our brass hardware in nickel on request. Please contact us for details.
Horton Brasses Inc., 49 Nooks Hill Road, Cromwell CT 06416, 800-754-9127