Edinburgh
In 1755 he was enticed by Lord Kames to become Professor of Chemistry and Medicine at the University of Edinburgh. It was in Edinburgh, in 1756, that he gave the first documented public demonstration of artificial refrigeration. Cullen used a pump to create a partial vacuum over a container of diethyl ether, which then boiled, absorbing heat from the surroundings. This created a small amount of ice, but the process found no commercial application.
From 1757 he delivered lectures on clinical medicine in the Edinburgh Royal Infirmary.
On the death of Charles Alston in 1760, Cullen at the request of the students undertook to finish his course of lectures on materia medica; he delivered an entirely new course, notes of which were published in an unauthorized edition in 1771, but which he re-wrote and issued as A Treatise on Materia Medica in 1789.
On the death of Robert Whytt, the professor of the institutes of medicine, Cullen accepted the chair, at the same time resigning that of chemistry. In the same year he had been an unsuccessful candidate for the professorship of the practice of physic (medicine), but subsequently an arrangement was made between him and John Gregory, the successful candidate, by which they both agreed to deliver alternate courses on the theory and practice of medicine. This arrangement continued until the sudden death of Gregory in 1773. Cullen was then appointed sole professor of the practice of physic, and he continued in this office until a few months before his death. He died on 5 February 1790.
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