1913] K. A. Hasselbaich 371 



present the difficulty that the potential changes in an unaccountable 

 nianner when the liquid in the electrode vessel is at rest. For this 

 reason I have proposed, as a normal method in measuring biological 

 fluids, that the shaking should be mechanical and permanent, even 

 during the reading of the electrometer. The electrode vessel is seen 

 in Plate 3, Fig. i. The arrows indicate the direction and extent 

 o£ the movement. While the shaking takes place, the electrode is 

 constantly immersed in the liquid. 



It is easily seen that this electrode vessel, by another arrange- 

 ment of the T-tube, may also be used in measurements which permit 

 hydrogen to be led through the liquid. This property of the vessel 

 may be of use, e. g., in efforts to control the correctness of the 

 electrode by measurement of " Standard Solutions " of a known 

 hydrogen-ion concentration. 



Fig. 2 (Plate 3) shows an electrode vessel used by me for 

 small quantities of fluid, especially in determinations of the hydro- 

 gen-ion concentration in 2-3 c.c. of human blood to which some 

 hirudin is added. The blood may be taken f rom the lobe of the ear ; 

 it is saturated in a glass syringe by rotation with about 20 c.c. of 

 the alveolar air of the individual. The electrode, F, is saturated 

 with a current of hydrogen flowing in the direction A— > B -» D -^ E. 

 D is a groove in the inner part of a ground glass stopper lubricated 

 with Vaseline and, during the flow of the hydrogen, it is turned so 

 as to be opposite the hole E in the outer wall of the apparatus. The 

 Saturation with hydrogen being completed, D is turned, as shown 

 in Fig. 2 (Plate 3), and the cock B, which must be quite free 

 from Vaseline, is turned around so that the first portion of the 

 liquid from the syringe passes through A and down into the rubber 

 tube C. The electrical connection between the liquid in the elec- 

 trode vessel and the Solution of potassium chlorid (Fig. i, Plate 3) 

 takes place along this route. When cock B is then turned as shown 

 in the figure (Fig. 2, Plate 3), and cock H (which is carefully 

 lubricated) is opened, the liquid rises in the electrode vessel as high 

 as the side-tube ; H is now closed, B turned around, and the syringe 

 disconnected. The shaking of the apparatus and the reading of the 

 electrometer may now be started, 



When we are dealing with blood or other fluids containing dis- 



