Background: Linus Carl Pauling (; February 28, 1901 - August 19, 1994) was an American chemist, biochemist, peace activist, author, educator, and husband of American human rights activist Ava Helen Pauling. He published more than 1,200 papers and books, of which about 850 dealt with scientific topics. New Scientist called him one of the 20 greatest scientists of all time, and as of 2000, he was rated the 16th most important scientist in history. Pauling was one of the founders of the fields of quantum chemistry and molecular biology.
Context: In his first semester, Pauling registered for two courses in chemistry, two in mathematics, mechanical drawing, introduction to mining and use of explosives, modern English prose, gymnastics and military drill. He was active in campus life and founded the school's chapter of the Delta Upsilon fraternity. After his second year, he planned to take a job in Portland to help support his mother. The college offered him a position teaching quantitative analysis, a course he had just finished taking himself. He worked forty hours a week in the laboratory and classroom and earned $100 a month, enabling him to continue his studies.  In his last two years at school, Pauling became aware of the work of Gilbert N. Lewis and Irving Langmuir on the electronic structure of atoms and their bonding to form molecules. He decided to focus his research on how the physical and chemical properties of substances are related to the structure of the atoms of which they are composed, becoming one of the founders of the new science of quantum chemistry.  Engineering professor Samuel Graf selected Pauling to be his teaching assistant in a mechanics and materials course. During the winter of his senior year, Pauling taught a chemistry course for home economics majors. It was in one of these classes that Pauling met his future wife, Ava Helen Miller.  In 1922, Pauling graduated from Oregon State University (known then as Oregon Agricultural College) with a degree in chemical engineering. He went on to graduate school at the California Institute of Technology (Caltech) in Pasadena, California, under the guidance of Roscoe Dickinson and Richard Tolman. His graduate research involved the use of X-ray diffraction to determine the structure of crystals. He published seven papers on the crystal structure of minerals while he was at Caltech. He received his PhD in physical chemistry and mathematical physics, summa cum laude, in 1925.
Question: What did Pauling major in at Oregon State University?

Answer:
chemical engineering.