James H. Stack, 74, a retired special assistant to the executive director of the American Chemical Society and a former head of the organization's department of public and member relations, died of myelofibrosis June 23 at his home in Silver Spring.

Mr. Stack, who was born in New York City, graduated from Cornell University and earned a master's degree in education at New York University. He later joined the old New York Herald Tribune.

In 1945, he went to work for the American Chemical Society news staff in New York. In 1960, he transferred to the society's Washington headquarters as head of the division of public, professional and member relations, a forerunner of the division of public and member relations. In 1972, he became a special assistant to the executive director. He retired in 1973.

Mr. Stack was a member of the Public Relations Society of America, the National Association of Science Writers and the National Press and University clubs. He also was a member of the St. John the Baptist Church in Silver Spring.

Survivors include his wife, Helen T., of Silver Spring; two sons, William T., of Roanoke, and Robert T., of Germantown; a daughter, Elizabeth A., of Arlington, and three grandchildren.