13468. Humphreys, W. J.   Volcanic Dust and Other Factors in the Production of Climatic Changes, and Their Possible Relation to Ice Ages.   The Franklin Institute, 1913, Journal, 131-172, 5 figures.   Printed wraps, minor previous owner marks, usual signs of use and age, text in very good condition.    $16.00

10824. Sampson, E.   Mineral Commerce and International Relations.   Franklin Institute, 1936, Journal, 221 (1) : 1-58, 23 figures.   Printed wraps, signs of age discoloration, edge wear, and one corner is bumped, text in very good condition.    $11.00