(977) 
form, the vapour pressure suddenly increases and then remains 
constant until the salt is completely converted into the second hy- 
drate. Similar sudden increases occur when a third or fourth 
hydrate is formed. But totally different is the course of the vapour 
pressure line in the case of carbon monoxide-haemoglobin; no dis- 
continuities occur, the line commences with a nearly horizontal part, 
turns at first the convex side downwards, acquires a point of inflec- 
tion and at a still greater degree of imbibition it turns the concave 
side downwards '). 
Afterwards I investigated the crystalline albumin from seeds of 
Cucurbita Pepo, a globulin prepared in large quantities by Dr. G. 
GRrÜBLER in 1881 by extraction with warm solutions of common 
salt). I was enabled to make use of a quantity of the substance 
prepared by Dr. GrÜBLER personally; it consisted of beautifully 
formed octahedral crystals and in other respects it also conformed 
to the description given of it by GRÜBLER. 
The method of the vapour pressure determinations in these and 
further substances was the same as that followed in the case of the 
amorphous substances. The hygrometrie line is shown in the illustra- 
tion; it agrees in form with that of the carbon monoxide-haemoglobin. 
As a third example I investigated the crystalline Bence Jones’s 
albumose, which Miss A. GRUTTERINK and Miss WeEEVERS DE GRAAFF 
have prepared from pathological human urine”). The substance used 
for the research was kindly handed over to me by Miss GRUTTERINK ; 
she had freed it, by washing with water and decantation, as much 
as possible from ammonium sulphate. The substance consisted of 
beautiful prismatic, presumably hexagonal crystals. Here also an 
S-shaped line with a continuous course was obtained (see illustration). 
Besides these three albuminous bodies, I also investigated a erys- 
1) Hopre SeyrER and others (Schifer’s Textbook of Physiology I, p. 205) are 
of opinion that a fundamental difference may be made between the water of imbibition 
which is given off on drying at the temperature of the room and that retained 
until the temperature reaches 115° C. The latter, represented in the hygrometric line 
by the almost horizontal part, is called by them the “water of crystallisation” 
of the substance. In my opinion there is no sufficient reason for such a funda- 
mental distinction between the parts of a same continuous line. Moreover, the same 
phenomenon is found in amorphous imbibing substances (even in cases of unlimited 
imbibition power, such as serumalbumin and gum arabic) which are presumably 
liquids of very greal viscosity and where there can be no question of water of 
crystallisation. Even in these cases the substance dried at room temperature still 
loses a little water when heated to 1100, 
2) Journ. f, prakt. Ch. 23, p. 97—137. 
3) Zeitschr. f. physiol. Chem. 34, p. 893—407, 
