Eugene Sullivan, an American chemist, developed Pyrex glass in the 1900s. Pyrex was the first temperature-resistant glass that could withstand the extreme heat of the oven. The glass needed to have low-expansion properties; this meant that it would not quickly contract when transferred from a high-temperature environment, like an oven. It would not quickly contract then shatter to a significantly low-temperature setting. Pyrex today is still what we associate with any oven-proof glass we use.