George Karnofsky sang in a men's chorus, played the violin, raised two children and hiked the mountains of Europe and Pennsylvania with his wife of 67 years, Florence.

But his mind, or at least part of it, was always on his engineering work, fine-tuning an extraction process that separates liquids from solids in everything from soybeans and beer hops to ocean water and tar sands, according to his wife. Even after retirement, Mr. Karnofsky kept up with his profession, publishing his final article in Chemical Engineering News at the age of 90.

Mr. Karnofsky, of Mt. Lebanon, died Monday. He was 93.

"He was a man who was consumed by what he was doing, as many scientists are," said his wife.

Mr. Karnofsky was born in Brooklyn, N.Y., and graduated summa cum laude from The Cooper Union for the Advancement of Science and Art in New York City, then earned a master's degree in mathematics from Purdue University.

The Karnofskys, who had married in 1941, moved to Pittsburgh in 1943. Mr. Karnofsky began working for the Blaw-Knox Co., which ultimately became the Dravo Corp., and earned numerous patents in the United States and abroad, according to his family.

Called to service during World War II, Mr. Karnofsky was found to have a mild form of tuberculosis, and he worked on small rockets for the Army during his recovery.

After the war, Mr. Karnofsky's solvent-extraction inventions covered a wide range of substances, including separating liquids and solids in cottonseed, fish, salt from ocean water and hops. In the 1970s, he patented a process for the extraction of oil from tar sands, and his key invention, the Rotocel Extractor, helped transform the worldwide soybean industry by significantly increasing the amount of oil extracted from the bean.

After their son and daughter entered college, the Karnofskys began traveling more to England and to Europe, taking long hikes throughout the continent. They also continued hiking in Pennsylvania on the weekends; of all the places they hiked in Europe and the United States, their favorite was the Laurel Highlands Hiking Trail, 70 miles long with a creek running alongside much of it.

"You had this feeling of remoteness and quietness, but it wasn't so remote that you felt uneasy, and at the same time it had a certain amount of vigor," said Mrs. Karnofsky. "Then we would drive home listening to the Steelers game and then in the evening, we'd play bridge. We had about 50 years of that."

After his retirement at age 68, Mr. Karnofsky remained interested in chemical engineering, but he also became intrigued by a new and potentially more difficult skill: baking bread. French bread, in particular.

For Mr. Karnofsky -- who, as a young man, once asked his wife how to make a sandwich -- it was a skill he never quite mastered. French flour, it turned out, was a vital element of making authentic French bread.

"He got great slabs of stone -- he was scientific about it, you see -- that made my oven racks bend, and he put in water," said his wife. "He was trying to imitate the quality of French bread -- not just the quality of it, but the flavor of it, the texture of it."

In his final years, Mr. Karnofsky lived at Covenant of South Hills with his wife, who is 91. He also is survived by his son, Joel, of Berkeley, Calif.; and his daughter, Ellen Hubbard, of Oxford, England; and a granddaughter.

The family is not holding a funeral at Mr. Karnofsky's request.