Construction of a circular Warburg apparatus for 32 manometers.

The scope of new investigations made it desirable to use a Warburg apparatus for 32 manometers instead of 14, as usual in our laboratory. A circular thermostat was chosen for this apparatus. This made it possible to move the manometers around the thermostat, simplifying inserting and reading of the manometers by the manipulator. Moreover the location in the room is subject to less restrictions as the apparatus need not be accessible on 3 sides as is the case with a rectangular water bath and two rows of manometers. The construction had to meet the following requirements: I. the parts had to be machined from normal sizes of steel, brass and aluminium profiles and sheets; 2. castings could not be used, as these are generally too expensive to use in an apparatus which is not built in series; 3. the parts had to be machined in a normal laboratory workshop with a lathe of 61,/4" height of centres, 3~" between slide and centre, and Io ~ height of centres with gap piece removed. Larger circular plates (Fig. 3, (I7)), which had to be shaped in a factory by auto-genous cutting, should not require further machining of the plane sides or the inner circle. (The manner of machining the circumference of the manometer plate (Fig. 2, (2) is described later on.) ; 4. the manometer holders should correspond with those already present in the laboratory to ensure interchangeability. As to this requirement it is stressed that in case of different types of manometer holders certain self-evident dimensions in the drawing have to be changed. The Warburg flasks are pivotally shaken, the axis is placed in the centre of the scale behind the manometer limbs. The menisci are hardly agitated by this arrangement and the rotatory movements of the manometer limbs are minimal. The rotation of the knurled knob for the manometer adjustment did not interfere at all with the adjustment of the manometers during shaking. Should manometers be designed especially for this kind of apparatus, it would be advisable to locate the adjusting knob as close as possible to the axis of rotation.