254. REPORTS ON THE STATE OF SCIENCE.—1914. 
weakened or the chemical affinity is strengthened. Now, the two 
components in the coloured substances being distended in some degree, 
I propose for this special condition of matter the name of distension. If 
we accept this, have we created a new name only, or does matter in 
this condition really show new qualities? It seems to me that we 
have to deal with a peculiar condition of matter, which deserves a 
more elaborate study than it has met till now. I will not enter again 
into some special qualities, which have already been mentioned—the 
photoelectric effect and so on—but I should like to point out that 
matter in the distension state shows a strongly strengthened absorption 
of light. 
We noticed with regard to ammonium chloride the yellow-greenish 
after-colour of the chlorine. Now, cathode rays, as used in these 
experiments, will not penetrate any deeper than one-hundredth of a 
millimetre into the salt. In such a thin layer even pure liquefied 
chlorine would not show any perceptible colour. But besides this it 
must be noticed that we observe this after-colour at the temperature 
of liquid air, and that chlorine at this temperature, as Dewar and 
Moissan observed, is snow-white, even in thick layers. In a similar 
degree the brown colour of bromine is weakened at low temperatures. 
Now, if nevertheless we observe at this very low temperature the marked 
characteristic colours of chlorine and bromine, we must conclude that 
the absorptive power of these substances has become a multiple of 
its ordinary value. One may observe this strengthening of the absorp- 
tive power directly in the pure sulphur. Sulphur likewise turns into 
a snow-white substance if cooled by liquid air. But when the cathode 
rays fall on the white sulphur it takes immediately a yellow-reddish 
colour. It is a real after-colour, because at constant low temperature 
the colour is destroyed by daylight. 
Now, since the strengthening of light-absorption occurs in this 
elementary substance, it becomes evident that the cause cannot be 
any chemical process, but only a physical allotropy. The special 
character of this allotropy (which may be connected with an absorp- 
tion of electrons) will not be entered on in a discussion here. Probably 
we have to deal with a polymerisation, so that, for instance, the 
yellow-reddish sulphur would be analogous to polymerised oxygen—to 
ozone. 
I have mentioned already that the first-class after-colours are 
gradually destroyed by incident daylight. A peculiar phenomenon is 
connected with this destruction of colour. I found that after the day- 
light had fallen on the coloured substances, even for the shortest time? 
most of them showed a marked phosphorescence of long duration. 
I have observed this phosphorescence even in substances which had 
been coloured twelve years ago and had been kept in the dark since 
that time. The diffused dim light of a gloomy November day, when 
falling through a window on the coloured substance for one or two 
seconds only, is sufficient for the production of this phosphorescence 
in a marked degree. If you allow the daylight to fall several times 
on the same spot, then the colour is weakened at this spot, and we 
come to the presumption that the loss of colouration is generally 
