Dr. William Cullen was a scottish-born medical doctor whose career later turned to chemistry. He began practicing medicine in Glasgow as a surgeon's apprentice before becoming the ship's surgeon on a British merchant vessel. In 1732, he returned to Scotland to start up his own medical practice, meanwhile continuing his studies of medicine at the University of Edinburgh. It was there that Cullen developed a passion for chemistry and helped found the Royal Medical Society. After he'd completed his own courses and received his M.D. from Glasgow University, Cullen was awarded with Britain's first independent lectureship in Chemistry and became the president of the Faculty of Physicians and Surgeons of Glasgow.
It was around this time that he gave the first documented demonstration of artificial refrigeration. In his demonstration, Cullen used a pump to create a small vacuum over a container of diethyl ether. When the deithyl ether began to boil, it absorbed the heat from the container's surroundings, causing it to cool. This was recorded in his only published chemistry-related paper, "Of the Cold produced by Evaporating Fluids, and of some other Means of producing Cold".
While never making any scientific discoveries himself, he was known for being quite the capable teacher. His radiant enthusiasm and demostration-filled lectures drew large classes. The largest of which consisted of 145 students, with some having attended his class more than once before.
Cullen eventually resigned his career in chemistry to become a professor of medicine at Edinburgh. He continued to hold his position there up until the last few months of his life at the age of 79.