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.