( 962 ) 
On no account must imbibition be confounded with the porosity 
of some solid substances such as bricks, gypsum, and others which 
by surface adsorption and capillarity can absorb liquids in vészhle 
preformed pores. NXeru *) in 1858 already pointed out the difference 
between these two properties. In the porous absorption of water, the 
particles of the solid body are not forcibly separated; there is no 
increase of disgration, therefore no increase in size and no loss of 
cohesion. Typical imbibition is, therefore, sharply distinguished from 
typical porosity. 
It is principally among the products derived from living organisms 
that the imbibition power is often, in fact almost regularly, met with. 
Not only nearly all such substances (cellular walls, fibres, flour, 
wood, whalebone, leather, horn, ete.) possess swelling power but the 
pure physiologico-chemical compounds derived therefrom appear to 
possess these properties also. 
Yet, the imbibition power is not limited exclusively to substances 
of vital origin. It is also observed in synthetically prepared and in 
inorganic substances; as instances, | cite copper ferroryanide, clay, 
tricaleium phosphate, and silicic acid. 
The solid substances capable of imbibing water *) are amorphous, 
crystalline, or organised. The majority is-amorphous that is to say, 
possesses no visible regular arrangement of particles *). 
1) Die Stärkekörner, Zürich, F. ScHULTHESS, 1858, p. 332, 343. 
2) Substances are known which absorb liquids other than water; caoutchouc, 
for instance, imbibes ether, oil, pyridin, and even liquid carbon dioxide; nilro- 
cellulose swells in alcohol-ether mixtures and in nitroglycerol It is possible that 
the imbibition jaws in some of these organic liquids are more simple than in the 
case of water because this is partly associated to complex molecules (perhaps 
HO) and because the association degree of the imbibed water must necessarily 
alter. For physiological purposes the behaviour with water is, for the moment, the 
most important matter and therefore, 1 will limit myself to this. 
On the imbibition in aqueous solutions of salts, whereon Hormeister, Spiro, 
Pauw, Wo Osrwatp, H. Fischer among others have made interesting experiments, 
I will deal when | have dwelt on the imbibition power in pure water. 
5) In praclice it is sometimes difficult to decide whether an imbibing substance 
is amorphous or crystalline. For, the external form of a typical crystal, with ils 
regular limitation by flat planes, may be wanting without the substance ceasing 
lo be erystalline. On the other hand an amorphous swelling body may, owing lo 
tensions on drying, exhibit optical phenomena which remind one strongly of those 
by a crystalline substance (compare the experiments of Amprony, Ber. der Siichs. 
Gesellsch. d. Wiss. 1891 p. 349. The mere presence of anisotropism is, therefore, 
nol in the least sufficient to prove a substance to be crystalline. So long as erystal- 
lography does not threw more light on this obscure question, I think it best to 
look on, imbibing substance as amorphous, unless there is sufficient evidence to 
call it crystalline or organised. 
