This specification provides standard dimensional requirements for flat-bottom and round-bottom glass boiling flasks. Boiling flasks shall be in the following types: type I- flat bottomed: class 1 - tooled top, long neck; class 2 - ring neck, long neck; class 3 - ring neck, long neck, wicker protector; class 4 - standard taper neck, short neck; class 5 - standard taper neck, long neck. Type II- round bottomed: class 1-tooled top, long neck; class 2-ring neck, short neck; class 3-standard taper neck, short neck; class 4-standard taper neck, long neck; class 5-standard taper neck, short neck with side arm; class 6-standard taper neck, short neck with thermometer well; and class 7-ball and socket neck, short neck. Type III- heart-shape bottomed: class 1-standard taper neck, short neck. Necks on all single-neck flasks shall be circular in cross section and perpendicular to the center of the flask body. The top shall be strengthened and finished. Flat bottoms shall be in a plane perpendicular to the vertical axis through the neck of the flask. Round-bottomed flasks shall be spherical in shape to the point of juncture with the flask neck. The nominal capacity of a flask shall not exceed the actual capacity to the base of the neck.