PYREX® 100 mL Goetz Pear-Shaped Centrifuge Tube With Graduations manufactured by Corning is used for phosphorus determinations in iron and steel. The lower stem is graduated upward to 1 mL in 0.05 mL divisions. The body is graduated from 1 mL to 5 mL in 1 mL divisions; from 5 mL to 50 mL in 5 mL divisions; and from 50 mL to 100 mL in 10 mL divisions.