(981 ) 
acid (h = 0.96) for three days *). Just as Scuimper?) had found this 
for the imbibing albumin crystals, the swelling takes place here 
evenly in all directions so that the crystal form is retained. 
Summarizing, we notice that there is so great a resemblance 
between swelling erystals and mixed crystals that it is difficult to 
draw a line of limit. [f a crystal takes up another component to 
form a mixed crystal, it will, according to Rereers’ rule, increase 
in size; if the quantity absorbed is small, the increase in size may 
readily escape the notice of the observer, if large the crystal is seen 
to “swell”. 
The imbibition of crystals is, therefore, explained in an uncon- 
strained manner and without any additional hypothesis by the theory 
that the swelling depends on the formation of a solid solution. The 
other theories of swelling met here with great difficulties. 
Finally, I just wish to call attention to a fact which appears to 
me particularly interesting from a physico-chemical point of view, 
but the details of which are beyond the scope of this communication 
so that I prefer to devote to it a special article. I allude to the 
striking resemblance of the quantitative laws of the miscibility in 
the liquid and in the crystalline condition, at least in regard to the 
hygrometrie lines. Compare, for instance the form of this line in 
liquid sulphuric acid with that in crystalline basic zirconium oxalate 
and in crystalline quercitrin (see illustration); the form is quite the 
same. ‘This explains the analogy found in the form of the hygrometric 
lines of crystalline and amorphous swelling substances. 
The experiments with haemoglobin were carried out in the Phy- 
sidlogo-chemical Laboratory of the University of Utrecht (director 
prof. C. A. PrKELHARING), those with the other substances in the 
Physico-chemical Laboratory of the University of Amsterdam (director 
prof. H. W. Baknuis RoozeBoom, afterwards prof. A. Smits). 
1) Löwenstein observed that the crystals then become much softer and, finally, 
even liquefied. The same thing I have found in haemoglobin and edestin crystals 
which, at the imbibition maximum are so soft that they amalgamate when pressed 
between two porcelain plates, whereas in the dry condition they are hard and 
brittle. This fact is interesting in connection with the nature of liquid crystals: 
here we notice that crystals which are not liquid lacquire this property conti- 
nuously upon taking up a second component. 
2) Zeitschr. f. Krystallographie, 1880. 
