William T. Miller, a key scientist on the Manhattan Project team that developed the atomic bomb in World War II and a member of the chemistry faculty at Cornell University from 1936 to 1977, died Nov. 15 at the Cayuga Medical Center in Ithaca. He was 87.

In the late 1930s, Miller carried out research into chemically resistant materials from which he later developed the chlorofluorocarbon polymer used in the first gaseous diffusion plant for the separation of uranium isotopes, a crucial factor in the development of the atomic bomb. The fissionable isotope Uranium-235 is separated from the more abundant isotope Uranium-238 by selective diffusion of uranium hexafluoride gas through barriers, or filters.

The problem faced by researchers was creating process materials (lubricants, gaskets, pump oil) that would not react with the highly corrosive uranium gas. Because of his expertise in organofluorine chemistry, Miller was recruited to work on the Manhattan Project. He and his colleagues developed novel polymers that did not react with the uranium gas, making possible the separation of the fissionable isotope.

For this effort, U.S. Army Maj. Gen. Leslie R. Groves, the military leader of the Manhattan Project, sent Miller a letter to of commendation: "I wish to express my appreciation to you for the contribution you made to the development of the atomic bomb. The engineering research work you carried out resulted in the development of certain materials needed in the large production plant and was essential to our success."

Miller was born in Winston-Salem, N.C., in 1911. He earned a bachelor's degree in 1932 and a doctoral degree in 1935, both from Duke University. The following year, he was a Lilly Fellow at Stanford University. In 1936 he came to Cornell as an instructor, and he retired as a professor emeritus of chemistry in 1977.

In 1974, Miller received the American Chemical Society award for Creative Work in Fluorine Chemistry, and in 1986 in Paris he won the Moissan Centenary Medal in honor of Henri Moissan, who discovered the element fluorine in 1886. He was a member of the American Chemical Society and Britain's Royal Society of Chemistry.

He is survived by his wife of 47 years, Betty Robb Miller; his brother, Robert L. Miller of Panama City, Fla.; his nephews, Robert Miller of Belfast, Northern Ireland, and Richard Miller of Grosse Point Farms, Mich.; and his niece, Katherine Johnston, of Opelika, Ala.

A memorial service will be held on Saturday, Dec. 12, at Sage Chapel on the Cornell campus. Donations in his name may be sent to Cornell Plantations, One Plantations Road, Ithaca, N.Y. 14853, or to a charity of choice.