Vigreux columm for vacuum distillation of high boiling materials

The top joint is a combination cap, thread and joint to accommodate and seal other microscale apparatus. The O.D. of the top joint has an external thread to facilitate an o-ring and open-top phenolic cap. The internal or I.D. at the top is a ground [ST] 14/10 outer joint. Bottom is a [ST] 14/10 inner joint, and indents. Length stated is length of indents. Fabricated from borosilicate glass.