The best moroccos are those tanned entirely “acid-free,” or as nearly so as possible. “Niger” morocco, native tanned on the banks of the Niger River in Africa, and imported into England, is an acid-free leather used for expensive bindings. This leather is rather hard to secure, but its desirability is indicated by the fact that it is the only leather on which the severe tests described in the Report of the Committee on Leather for Bookbindings, elsewhere mentioned, had no effect.
CHAPTER VI
THE BOOK SHELVES
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LEATHER SLIP-COVERS