Workman at left checks pressure tubes filled with cellulose acetate membranes which permit fresh water to flow through but hold back salt and other dissolved solids. A closeup of the cellulose acetate semipermeable membrane, which is only 5/1000s of an inch thick, is at the right. The membrane may be the answer to large desalting operations.

Photo is dated 1966.

Photo measures 10 x 8.25 inches.