

When Dr. Cook was studying chemistry in the Yale graduate program in the 1930's, he had no interest in the field of explosives, said one of his sons, Merrill Cook, a Utah congressman and a business partner of his father's.

But when he took a job with DuPont in 1937, the company had its own ideas. ''He was a little surprised when they put him in the explosives group,'' his son said.

Dr. Cook immersed himself in the study of explosives, and a life's work was set.

At first his inventions were used in the mining and oil industries. But in 1941, he was asked to apply his new expertise to a daunting opponent: Hitler's armored divisions.

The bazookas then in use by the Allies, based on technology from the French, were unable to punch holes in the German tanks. Working with other scientists, Dr. Cook refined the shape of both the projectile and the blast it made on impact, enabling it to pierce the armor.

The new bazooka was introduced at the end of 1942 in the invasion of North Africa, and the weapon remained in use until the Korean War, when it was replaced by the rocket launcher.

In 1992, the Army gave Dr. Cook a special citation for his work.

In 1947, Dr. Cook returned to his native Utah and took a position teaching metallurgy at the University of Utah.

Over the years, he was called on for a range of jobs by industry and government, including helping investigate the 1947 disaster in Texas City, Tex., when a ship carrying fertilizer exploded in the harbor, killing hundreds of people.

The fertilizer was made from ammonium nitrate, and in the years that followed, Dr. Cook, using similar materials, developed ANFO explosives, made from ammonium nitrate and fuel oil. He also formed companies to produce a liquid form of the explosive called a slurry, which proved an invaluable tool for companies extracting ores from open-pit mines and a source of wealth for the Cook family.

Slurry explosives, unlike the risky dynamite and other nitroglycerine-based materials they largely replaced, are powerful but highly stable and can be pumped into trucks and poured where needed. They are unaffected by the presence of water, which had long made blasting difficult for open-pit miners.

Melvin Alonzo Cook was born in Garden City, Utah, on Oct. 10, 1911, the son of Alonzo Laker and Maude Osmon Cook.

Besides Representative Cook, he is survived by his wife, the former Wanda Garfield; two other sons, M. Garfield, Krehl O.; and two daughters, Barbara Peterson and Virginia Sanders, all of Salt Lake City. He is also survived by two brothers, Owen and Vernon; and three sisters, Vera Hunsaker, Maurine Winterton and Lois Canning.

Dr. Cook maintained close ties to the Mormon Church, and apart from his contributions to explosives, he made a reputation for himself in academic circles -- and angered some colleagues -- as an outspoken advocate of a sort of science-based creationism. Marshaling his broad knowledge of science for the cause, he argued that the theory of evolution violated the rules of nature, and suggested that the earth was far younger than generally believed by mainstream scientists.

Dr. Cook held about a hundred patents, and in 1968 the Swedish Royal Academy of Engineering Science awarded him the Nitro-Nobel Gold Medal for his work.

Sometimes, though, the technology Dr. Cook helped bring into being worked too well, and in ways he had not intended. ANFO explosives are easy to make, and have been used in terrorist bombings like that of the Alfred P. Murrah Federal Building in Oklahoma City in 1995, which killed 168 people.

Dr. Cook once told an interviewer that he had known immediately after that explosion what the terrorists had used to destroy the building.

''It was so simple to initiate, yet so powerful,'' Dr. Cook said.

And he rued the misuse of an invention that had been intended to make blasting safer.

''My objective,'' he said, ''has always been safety and saving lives.''