acidic paper v.3:no.1(1922:May)-v.61:no.4(1984) acidic paper pH pen test brittle covers v.3:no.1(1922:May)-v.8:no.2(1928:Jan.),v.10:no.2(1930:Jan.) brittle covers double fold test--breakage on second fold brittle paper v.8:no.4(1928:May),v.10:no.1(1929:Nov.),v.29:no.1(1951:Nov.) brittle paper double fold test--breakage on second fold stained pages v.26:no.2(1949:Jan.)-v.26:no.3(1949:Mar.),v.32:no.1(1954:Nov.)-v.32:no.4(1955:May) warped/cockled v.26:no.2(1949:Jan.)-v.26:no.3(1949:Mar.),,v.32:no.1(1954:Nov.)-v.32:no.4(1955:May)