121 
to the large one. To bring this about some of the clear fluid in 
the latter is taken into a pipette and all the precipitate in the small 
tube is washed into the large one. In the same manner the surface 
of the small tube is washed, so that all the BaSO, gets into the 
large tube. 
We might wish to bring the contents of this tube (12'/, ce.) into 
the funnelshaped part of the chonohaematocrite, but the latter holds 
only about 2'/,cc. Therefore we centrifugate; the greater part of 
the clear fluid is removed and the sediment is mixed with the rest 
of the fluid. After the capillary tube has been filled with mother 
liquor by means of a glass tube drawn out into a capillary, this 
turbid mass is brought into the funnel-shaped part, We now centrifugate, 
the clear fluid is removed from the funnel-shaped part and replaced 
by the BaSO, which had remained behind in the wide tube. It 
need hardly be said of course that the BaSO, adhering to the inner 
and outer surface of the small tube must be transferred to the 
wide tube by being washed with mother liquor. Now the whole is 
centrifugated until the volume remains the same, which takes about 
half an hour *). 
We will now state the results of some experiments with some 
pure Na,SO, solutions. They are all double-experiments. 
4. Results of some microvolumetrical SO,-determinations. 
TAB EE. 
Proportionality between the volume of BaSO, precipitate and the SO, used. 
Number of divisions of BaSO, 
7.5 cc. of HCI sulphate-solution +5 cc. of ae 5 
BaCls-solution containing acetone. average, calculated 
I II Ill 
1) 2.cc.ofNa,SO, 10.aq.2/)-+2Yecc.of HCI 1:1-+-3cc.of water! 41 | if 
2) 2 ” + 21/2 ” +3 et at 
3) 3 21, ; 2 68 
: li ie | | 62 Ìx41=615 
4) 3 ‘ TL y. > 1-2 PDK De: a 
5) 4 . 21/, 5 1 eh A | 
nie eee a | | 82 5 X41 = 82 
6) 4 ” +245 ” aol | ? 
7) 5 ’ Baer, 103 | 
Val, | 102.5, X41 — 102.5 
8) 5 r ail), 8 102.5 | 
1) Compare the article: Une méthode simple pour le dosage de minimes quantités 
de potassium. Receuil des Travaux Chimiques ‘des Pays-Bas et de la Belgique. 
Tome XXXV 1916, 225. 
