McCarthyism is now a part of the American language, a word connoting demagoguery and inquisition. That is the legacy of Senator Joseph McCarthy, the World War II veteran who in the early 1950's launched a campaign to stamp out so-called Communists in government. He gained national prominence, only to go into a sudden decline in late 1954 when he was censured by the United States Senate. Historian David M.Oshinsky chronicled McCarthy's rise and fall in A Conspiracy So Immense: The World of Joe McCarthy, a book columnist Jack Anderson described as "a must read both for those who lived through the era and for those who want to know what McCarthy was all about" [Free Press, $9.95]. In observance of the 40th anniversary of the Los Alamos atomic explosion, Atheneum recently republished a paper edition of Lansing Lamont's Day of Trinity, a work first published in 1965 and the first full account of the atomic explosion in July 1945 that has haunted mankind ever since [$11.95]. The role that advertising has played in shaping American life in this century is as immense as it is incalculable, and an account of what has been called "this country's most characteristic institution" is set forth in Stephen Fox's The Mirror Makers: A History of American Advertising and Its Creators, now available as a Vintage Book [$4.95]. Vintage is also offering Orville Schell's Modern Meat: Antibiotics, Hormones, and the Pharmaceutical Farm, which Studs Terkel called "a dietary sequel to Silent Spring" [$5.95]. Touchstone Books has republished Charles L.Mee, Jr.'s The Marshall Plan: The Launching of the Pax Americana, an almost day-by-day account of just how the plan that brought Western Europe to its feet after World War II was devised and carried out [$8.95]. Touchstone has also published revised and updated editions of two works dealing with economics, one being Herbert Stein's Presidential Economics: The Making of Economic Policy from Roosevelt to Reagan and Beyond [$9.95], the other being Louis Rukeyser's What's Ahead for the Economy [$8.95]. Cornell Paperbacks had come out with a revised edition of William E.Leuchtenburg's In the Shadow of FDR: From Harry Truman to Ronald Reagan, a work that examines the influence our only four-term president had on all the chief executives who succeeded him [$8.95]. Illinois is offering a paper edition of Robert M. Crunden's Ministers of Reform: The Progressives' Achievement in American Civilization, 1889—1920, a depiction of an era of controversy and innovation in American history [$10.95].