   thumb|a pyrex measuring cup manufactured c. 1980, featuring graduations in both metric and u.s. customary systems. pyrex (trademarked as pyrex) is a brand which was introduced by corning incorporated in 1915 for a line of clear, low-thermal-expansion borosilicate glass used for laboratory glassware and kitchenware. it is now made of tempered glass. corning no longer manufactures or markets pyrex-branded borosilicate glass kitchenware and bakeware in the us, but pyrex borosilicate products are still manufactured under license by various companies. world kitchen, llc, which was spun off from corning in 1998, licensed the pyrex brand for their own line of kitchenware productsdifferentiated by their use of clear tempered soda-lime glass instead of borosilicate. == history == thumbnail|right|newspaper ad showing pyrex bakeware from 1922. borosilicate glass was first made by german chemist and glass technologist otto schott, founder of schott ag in 1893, 22 years before corning produced the pyrex brand. schott ag sold the product under the name "duran." in 1908, eugene sullivan, director of research at corning glass works, developed nonex, a borosilicate low-expansion glass, to reduce breakage in shock-resistant lantern globes and battery jars. sullivan had learned about schott's borosilicate glass as a doctoral student in leipzig, germany. jesse littleton of corning discovered the cooking potential of borosilicate glass by giving his wife a casserole dish made from a cut-down nonex battery jar. corning removed the lead from nonex, and developed it as a consumer product.corning pyrex bakeware, carroll m. gantz, design chronicles: significant mass-produced designs of the 20th century, schiffer publications, ltd. 2005 pyrex made its public debut in 1915 during world war i, positioned as an american-produced alternative to duran. a corning executive gave the following account of the etymology of the name "pyrex": {{quote|the word pyrex is probably a purely arbitrary word which was devised in 1915 as a trade-mark for products manufactured and sold by corning glass works. while some people have thought that it was made up from the greek pyr and the latin rex we have always taken the position that no graduate of harvard would be guilty of such a classical hybrid. actually, we had a number of prior trade-marks ending in the letters ex. one of the first commercial products to be sold under the new mark was a pie plate and in the interests of euphonism the letter r was inserted between pie and ex and the whole thing condensed to pyrex.{{cite journal | journal = [[ameri
1915_introductions Boron_compounds Corning_Inc. Glass_trademarks_and_brands Glass_types Kitchenware_brands Low-expansion_glass Transparent_materials