A modified method for the calibration of warburg flasks and manometers.

During the last few years several methods have been described for the calibration of W a r b u r g flasks and manomete r s wi th mercury1, ~ ,8. Al though in all these methods the calibration is carried out in two steps, so t ha t it can easily be performed by one operator, they have the disadvantage, in our view, t ha t the flasks m u s t always be filled wi th so much mercury t ha t it exact ly reaches a predetermined mark on the side-arm capillary when the flask is seated on the ground joint of the manometer . This ad jus tmen t of the volume of mercury gives unnecessary and t ime-consuming work. The following method, which does not possess this difficulty, is very rapid, and has given complete satisfaction in our labora tory for a num ber of years. a. Flask F is filled wi th so much mercury, paying due a t tent ion to the removal of t rapped air bubbles, t ha t when it is connected to the manomete r in posit ion i, the mercury rises to some a rb i t r a ry point M 1 in side-arm capillary C 1. This poin t is marked wi th a glass-marking pencil. Flask F is detached and the mercury is poured into a tared beaker. b. Wi th the manomete r in posit ion 2, a shor t rubber tube R, closed at one end wi th a shor t piece of glass rod and filled wi th mercury, is pushed over the capillary at opening T1, while stopcock S is open. The rubber tube is pushed on so