1651 
glass and front pane, through the sol to the posterior electrode. 
The motion now proved to have more the character of an electro- 
endosmotie process than that of cataphoresis; the narrow crevice 
between the two glass plates acted as a capillary opening. With a 
few flakes which are permanently luminous it could be ascertained 
that, on interrupting the current, the liquid flowed back. Hence, we 
have been able to incidentally make here an observation. as to 
sagittally flowing liquid; the result corresponds with the expectation, 
7. The fact of the disappearing of intenference images can also 
be observed without ultramicroscope. The fact stated can also be 
explained in this way that particles situated with their longitudinal 
axis parallel to the illumination direction do not disperse any, or 
but very little, light sideways. The Tynpari phenomenon must, 
therefore, differ strongly with a V,O, sol when this is submitted 
to cataphoresis, first with the electric field parallel, then with that 
field perpendicular to the luminous beam. 
In a planeparallel vessel with square horizontal section was sus- 
pended on each wall a strip of tin foil. Two foils placed opposite 
each other were, at an equal height, provided with a small round 
opening, through which could pass a beam of light. As illuminating 
beam I used that of the slit-ultramicroscope after removing the back 
condenser, the objective AA (Zxriss). The tin foils were now connected 
with a commutator, which rendered it possible to let the current 
of a Rurmkorrr coil (of a somewhat larger type than the one 
discussed previously) pass at will between each pair of opposite tin 
electrodes. With this now a strong fading, or else a fierce flashing 
of the TyNparr cone, appeared if this was observed by looking 
through the vessel from above. ; 
By way of a “cheek”, this experiment was repeated with distilled 
water, with a red gold sol and with a Fe,O, sol (also with a sol 
three years old, respectively one that had been heated *) for 20 hours, 
at 100°); in those liquids, however, the phenomenon did not occur. 
Utrecht, March 1916. van 't Horr-Laboratory. 
1) See the article cited from the Jubilee-Edition ELSter and GEITEL. 
