Bui. U.S. B. F., 1917-18. PLATE XL. 
Fic. 1.—The churns, with buttons receiving polish by the use of acid and steam. Note the funnels from which acid solution 
drips into the churns. (See p. 77.) 
2.—The sorting room, in which skillful operators classify buttons into «2 grades. (See p. 77.) 
