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way; that is to say, it penetrates the crystal entirely, and, 
after a while, Silver Oxide is found occupying the place of, 
and of the same shape as the original Nitrate. This, however, 
is not at all surprising if we compare the atomie volume of 
Sodium, 24:8 with that of Potassium, 45:2. 
Osmosis through these molecular interstices, is in many 
other cases not only physical but chemical, since additional 
and important duties are performed which may explain 
many phenomena which have been hitherto imperfectly 
understood. The obscure chemical actions which we observe 
taking place in vegetable and animal cells, and which appear 
to be inexplicable, are always accompanied by Osmotic pro- 
cesses, the contents of the cell being separated by a membrane 
from the exterior liquid of a different chemical nature; we 
frequently in such cases find a production and separation of 
new compounds to occur. As in the crystal, every molecule 
occupies relatively an unalterable position, so there is a 
specific arrangement of the molecules composing the substance 
of the cell-wall, between the molecules of which there are 
molecular interstices. Where such molecular interstices do 
not exist, Osmosis cannot take place, and it is possible, if not 
probable, that these interstices are of various shapes and size, 
according to the kind of cell. Let us now imagine that the 
cell-wall possesses molecular interstices smaller than the 
molecular volume of the external body, then the Osmotic 
force can only be satisfied and an equilibrium established, by 
tearing asunder these molecules and the forming of new 
compounds, provided the power of resistance to such breaking 
up be not too great. As Nitroglycerine (relatively rich in 
NO, molecules) by motion (as a blow) is broken up into 
simpler compounds, so, for instance, the Sugar molecule 
(relatively rich in OH molecules) is, by shifting, pressing and 
stretching, broken up, and this process of splitting may take 
a different direction, according to the shape and size of the 
molecular interstices of the cell wall, in which they are in 
contact and through which they pass, provided the chemi- 
cal nature of the Sugar molecule permits of such action. 
Viewing the subject in this light, furnishes us with a simple 
