6.1.4 Variable-Speed Mechanical Stirrer, a suitable type,
equipped with a propeller-type stirring paddle. The rate of
stirring shall be sufficient to produce vigorous agitation without
spattering and without stirring air into the solution. A propeller
with blades 6 mm in radius and set at a pitch of 30 to 45° is
satisfactory. A magnetic stirrer is also satisfactory.
6.1.4.1 If an electrical stirring apparatus is used, it shall be
electrically correct and grounded so that connecting or disconnecting
the power to the motor will not produce a permanent
change in the meter reading during the course of the titration.
6.1.5 Burette, 10-mL capacity, graduated in 0.05-mL divisions
and calibrated with an accuracy of 6 0.02 mL. The
burette shall have a tip that extends 100 to 130 mm beyond the
stopcock and shall be able to deliver titrant directly into the
titration vessel without exposure to the surrounding air or
vapors. The burette for KOH shall have a guard tube containing
soda lime or other CO2-absorbing substance.
6.1.6 Titration Beaker, 250 mL capacity, made of borosilicate
glass or other suitable material.
6.1.7 Titration Stand, suitable for supporting the electrodes,
stirrer, and burette.