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§ 2. A second condition which the apparatus has to fulfil, is this that 
the mixtures which are to beexamined, can be properly stirred during 
the experiment. Of course there can be no question of an electromagnet 
stirrer inside the heavy steel vessel. The difficulty seemed the greater as 
during the experiment, and so also during the stirring the steel 
vessel, which itself is already very heavy, lias to remain connected 
without leakage with the compression pump and the manometer. 
We have finally succeeded in finding a construction meeting all 
demands; it rests on the following consideration. The pivot of a 
high-pressure cock may be turned round, without giving rise to 
leakages; we can just as well keep this pivot still, and turn the 
rest of the apparatus round it. Suppose the inlet tube, which con- 
neets the vessel of observation with pump and manometer, at the 
place of this pivot, and arrange the connection in such a way that 
the observation vessel can turn round this inlet tube as a pivot, then it 
must be possible to bring about the most efficient form of stirring 
viz. turning upside down the whole contents of the vessel of observation. 
This idea is realized in the construction represented by fig. 2. C 
is the inlet tube of the compression pump, it has a diameter of about 
15 mm.; the aperture is about 2 mm. wide. A prolongation D*) 
can be screwed on to the tube C, by which a projecting cone is 
pressed against a conical concavity of C. In this way a steel-to-steel 
closure is obtained, which is quite tight even at the highest pressures. 
As is shown in the figure, the piece D pierces with its carefully 
finished and polished part through the packing /, which is enclosed 
between two rings, and can be screwed so tightly by means of the 
gland in connection with the flange G, that leaking along this 
packing is prevented, though the pieces G and / with this packing 
can still turn round DC as pivot. To prevent DC from being pres- 
sed outside through the pressure on the end-plane of D, D is kept 
in its place by a gland H, a ball-bearing adjusted between D and 
H making it possible to screw M/ sufficiently tight without making 
the friction between DJ and M so considerable that it would hamper 
the rotation. The flange G is now again pressed against the obser- 
vation vessel 4 by means of the bolts A, which pass through if, 
and which are screwed into the observation vessel 4, and the nuts 
M. In this way the same steel-to-steel closure is applied as between 
Cand PD. By means of the handle V the pressure vessel 4 can, 
when everything is mounted and put under pressure, be rotated, 
1) This tube is only 12 mm externally (and has in correspondence with this 
also a somewhat smaller opening than GC) to make the pressure on the ball-bear- 
ings as small as possible. 
