BOD NATURE 
[May 28, 1914 
debted to Dr. H. B. Hutchinson and. Mr. A. 
yard for the photographs here reproduced. 
A suspension of clay in alcohol gives the opposite 
effect; in this case the preliminary “network does not 
seem ‘to appear. Isolated groups or single cells form 
active centres, from which other cells grow until the 
surface is covered. The cells are nearly hexagonal 
and sharply rectilinear, and frequently measure half 
cm. in diameter. There is a light spot in the middle 
Apple- 
of each, and the particles can be seen flowing up at 
The 
the middle and down at the sides of the cells. 
Fic. 1. Fic. 2. 
pattern persists for a few seconds and then fades 
away, only to reappear after a short interval. This 
periodic reappearance is very fascinating to watch. 
In all probability it is caused by small air currents 
flowing over the surface of the liquid, disturbing the 
rate of evaporation. 
I have occasionally noticed another very curious 
phenomenon in the beakers containing the clay sus- 
pension in dilute ammonia. Usually, “after the lapse 
of a few hours, the brown coloured mixture increases 
in opacity from top to bottom of the liquid. In the 
This stratification will persist indefinitely. The 
rings remain unbroken and gradually sink, at a rate 
‘below one cm. in twenty- four hours, as the suspen- 
sion slowly clears. The phenomenon seems to be 
quite fortuitous, and I have not been able, up to the 
present, to reproduce it at will. 
It is possible that it may be related in some manner 
to those forces producing the cellular structure, and | 
should be glad if some reader could supply me with 
information or references to it. 
B. A. KEEN. 
Rothamsted Experimental Station, Harpenden. 
THE KAISER-WILHELM INSTITUTE OF 
CHEMISTRY. 
DESCRIPTION of the objects of this Insti- 
tute has already been given in Nature of 
Feb. 23, 1911, in the report of a lecture delivered 
at the inauguration of the Kaiser-Wilhelm Gesell- 
schaft by Prof. Emil Fischer on January 11 of 
that year. 
The institute was formally opened by the Em- 
peror on Oct. 23, 1912. It is divided into sections 
each of which is under the direction of specialists 
with a consultative committee of experts. 
Beckmann is director of the chemical section and 
is assisted by Dr. Willstatter, who is head of the 
organic laboratories, and Dr. O. Hahn, who is 
engaged upon the study of radioactive substances. 
The institute is situated at Dahlem, not far 
from Berlin, and it forms a_three-sided block 
consisting of three floors and a basement. The 
top floor is occupied by Dr. Beckmann and has 
accommodation for about a dozen. workers, the 
first floor is apportioned to Dr, Willstatter, and 
Main building, with director’s and porter’s houses, of the Kaiser-Wilhelm Institut, Berlin, Dahlem. 
case mentioned this graduation is broken by one or 
two colourless horizontal rings, which appear round 
the side of the beaker. Thus, there is an increase in 
opacity from the surface to a depth of one or two 
cm., until the first ring is reached. The layer imme- 
diately below seems to be less opaque than the layer 
immediately above the ring, but chis may be purely 
an optical illusion. ~The liquid below the ring in- 
creases in opacity until the second ring is reached, 
when the appearance already mentioned is repeated. 
NO. 2326; Vorno3i| 
the ground floor to Dr. Hahn. In the basement 
are installations for vacuum and __ pressure 
machines, electric motors and accumulators, liquid 
air plant and cold storage rooms. The ventilating 
exhausts are in a chamber under the roof where 
distilled water is prepared. The main buildings 
are shown in the accompanying illustration. 
The first volume of researches issued by the 
institute and covering the period from April, 1912 
Die 
Re eet 
cee a 
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