ABSORPTION OF WATER 
57 
54. Demonstration of Osmosis. The contents of a 
hen's egg are enclosed by a porous membrane closely ap- 
pressed to the inside of the shell, except at the large end 
of the egg. At this end the shell, as may readily tie seen, 
is more porous than elsewhere, so that air readily enters, 
pressing the membrane in, and forming an air-chamber 
between it and the shell. With a sharp-pointed knife 
the shell may here be punctured, and with the aid of small 
scissors, removed so as to make an opening from }$ to 
% inch in diameter. The greatest care must be taken not 
FIG. 44. Experiment with an egg to demonstrate osmosis. A, at the 
beginning; B, about one hour later; w, water surface; s, support; m, egg- 
membrane. 
to puncture the membrane, which at this region, lies 
concave (Fig. 44). 
The contents of the egg are the yolk, the "white" 
(albumen), and an aqueous solution of various salts, which 
permeates the yolk and the "white." If, now, the egg 
is placed upright in a glass of water, so as to be completely 
covered by the water, we shall have realized the condi- 
tions for osmosis, the two liquids being the water outside 
and the aqueous solution inside the egg. Within a short 
time the less dense water will have passed through the 
membrane so much more rapidly than the dissolved salts 
