The purpose of this investigation is to develope the simple method for measuring directly the vapour pressure of high boiling liquid substances in the range above approximately 0. 5 millimeter of mercury. The construction of a new all-glass apparatus and the experimental data about some kinds of organic liquids are described.
The advantages of this apparatus are as follows.
(1) Vapour pressure of the sample is directly observed by means of the U-tube oil-manometer which is inserted into the chimney and f lled with its own liquid.
(2) There is a small nozzle at the top of the chimney, through which the vap ur is ejected out into the vacuum space. Hence, the gases which have been produced in the boiler or chimney by thermal decomposition are instaneously removed from the measuring system by vacuum pump.
(3) The apparatus has no rectifying power in th vapour cycle and so the total vapour pressure can be measured even when the sample consists of mixture species like petroleum fraction.