When you're baking with pyrex (which is made of borosilicate glass, the same type of glass most labware is made out of) the cookware isn't going into your brownies.
A scientist from the Corning Glass Works manufacturing company in New York brought his wife a sawed-off battery jar made of the so-called borosilicate glass, resistant to heat and mechanical abuse.
" In addition, refractive index can also be used to 'invisibility', for example, objects with high borosilicate glass materials can also be 'invisible' when moving in glycerol with a refractive index close to its own, " Chu noted.