116 
solution of the problem becomes practically impossible, at least when 
for instance daily. series of determinations have to be made. Che- 
mists often experience these difficulties no less. This will be the 
reason why a quantitative micro-analysis begins to develop itself, 
to which all the principles of the macro-analysis are applied, but 
with miniature implements; the micro-scales of Nernst are then 
mostly used as a weighing-apparatus. 
This method, however, has its drawbacks in being an analysis 
by weight, with all the difficulties attending it, which difficulties 
TP are still inereased by the fact that a slight mistake 
materially affects the results. Besides, the accuracy of 
the macro-gravimetrie method is anything but perfect. 
All this applies for instance to the quantitative determi- 
nation of the potassium and that of the SO,. It need 
not surprise us, therefore, that our knowledge of the 
K- and SO,- economy leaves much to be desired. 
As regards these two substances, however, I have suc- 
ceeded in finding another method, which consists in the 
volume of the precipitate beiny determined instead of 
the weight; this is done in a glass apparatus, the top 
part of which is funnelshaped, the neck being a calibra- 
ied capillary tube (see fig. 1). I might call the instru- 
ment a chonohaematocrite ‘), The calibrated capillary part 
has a eontent of 0.04 eub. centimetres, and is divided 
into 100 equal parts. The column of the precipitate is 
read off after being centrifugated to constant volume. 
This method combines accuracy with a simplicity 
hitherto unattained in the determination both of potas- 
Fig. 1. sium and of SO,. The potassium method I applied, has 
been described already *), it was lately used by me to solve physio- 
gical problems which could not be settled by the available methods *). 
I shall not dwell upon this potassium-method. It need only be stated 
that to the fluid containing the potassium-salt, a solution of sodium- 
1) From zvn (funnel) and haematoerite or blood-investigator, the name for. 
merly given by Hedin to a calibrated capillary tube, which he used to determine 
the volume of the red blood-corpuscles im blood. 
2) Hampurcer. Biochemische Zeitschrift '71 (1915) 415. Recueil des Travaux 
chimiques des Pays Bas et de la Belgique. T. 35. (1916), 225. 
3) HamBureer, Die Permeabilität von unter physiologischen Verhältnissen krei- 
senden Blutkörperchen für Kalium, nach einer neuen Methode untersucht. (Zusatz 
geringer Mengen von CO, Glukose, NaCl, KCl, NaOH und KOH). Wiener Med. 
Wochenschrift 1916 No. 14—15; Festnummer für Prof. 5. EXNER. 
