Test Tubes Made from Glass Tubing

Glass tubing is drawn continuously from molten glass and cut into lengths of about 1.5 m. A test tube is made from a length of it in the flame: turned until it softens, pulled apart to close one end, the closed end blown gently into a round bottom, and the open end heated and flared with a turnpin into a flange, which finishes the edge neatly and strengthens it so a cork can be pushed in without breaking it. Hard Bohemian glass was the usual test-tube glass in 1910.