Pyrex® is a type of glass that was originally introduced in the year 1915 to be used in laboratory glassware and home kitchenware as well. It is a borosilicate glass composed of approximately 51% oxygen, 38% silicon, 14% boron, 1% aluminum, 1% potassium, and 0.3% sodium (by mass). Since its original introduction in the early 1900s, a different company has now become responsible for making Pyrex^® glassware and they now make it from a soda-lime glass, which is different from the original formula. This new formula is cheaper to produce than the original and is more resistant to breaking when dropped, but has poorer heat resistance.