120 
GEDE and the wide tube we bring 7} ee. of the hydro- 
Gee chloric sulphate solution. It does not reach the upper 
) | PI 
rim of the inner tube. Then the 5 ee. BaCl,-solution 
are brought into the inner tube bymeans of a pipette, 
mixed with 5 drops of acetone and the wide tube is closed 
with a stopper. This stopper is pushed in so far that the 
narrow tube is gently pressed against the bottom. 
Then this tube is placed in a frame which can be 
turned on an axis. This frame can hold twelve such 
tubes. When the frame is turned round the reagent 
suddenly bursts into the sulphate-solution so that in 
an extremely short space of time a perfect mixture 
is obtained. To make quite sure the frame is turned 
a few times. Experience teaches that thus a very fine 
Fig. 2. precipitate is formed, the particles measuring on an 
WV, of actual average 0.0026 millimetres. The erystalshape at the 
piers usual magnitude (Leitz obj. 8, or 2) cannot be distinctly 
recognized; they are not needles, columns or crosses; to an untrained 
eye they suggest cubes that are not clearly cut. 
The drawing shows that the apparatus can also be turned 
mechanically, for instance by an electromotor. The rotation may 
also be brought about by substituting for the dise an iron bar 
——— == = —— —————SS 
Si ae = 2 ee 
Fig. 3. 1/, of the actual size. 
perpendicular on the axis. A solid brass cylinder can be moved 
along the iron bar and fastened with a screw. It depends on the place 
of this cylinder how rapidly the frame with its tubes will turn round 
when it is loosened (Cf. the article in the “Biochemische Zeitschrift” 1916). 
When the precipitate has been formed it can immediately be 
transferred to the chonohaematocrite. Therefore the small tube is 
taken out of the larger one and the latter is centrifugated for a 
short time, so that all the precipitate in it, is found on the bottom. 
Now that which is still found in the small tube must be removed 
