The book "The Ferrotype and how to make it" by EM. Eastbrook, is available once again.
Find it at Lindsay Publications along with other reprints such as,
The Negative, WH. Burbank - 1888
Silver Printing, Abney & Robinson - 1881
Photography in the Studio and Field, EM. Eastbrook - 1887
They all run around $13-$16.oo or so.
I hav the whole works and refer to them all the time.
Check out lindsaybks.com .