enclosing the Seeds of some of the Gramineae. Si 
Subsequently after draining and drying the grain in filter-paper as before 
it was found to weigh 14-459 g 1 ' ms. The grain had therefore absorbed 
1.950 grms. of moisture from the normal acid in which it had been steeped. 
This weight would represent 1-950 c.c. water abstracted from the original 
volume of normal acid if the skins of all the grains of barley employed 
were undamaged and had permitted the passage of water only through 
them; but on examination it was found that the skins of 7-2 per cent, of the 
grains employed had been injured and had admitted the passage of both 
acid and water to the interior of the grains. Consequently the volume of 
pure water abstracted from the acid solution and tending to concentrate it 
is i-8i c.c. (1-95 C.C.-014 c.c.). On subtracting this amount from the 
original volume of 15 c.c. of normal acid employed. 13-19 c.c. remain as 
the diminished volume of the acid solution calculated from the weight of 
water absorbed by the grain. 
On directly titrating 10 c.c. of the acid solution with normal (4-0 per 
cent.) caustic soda, it was found that ii-i c.c. were required for neutralization ; 
hence ii-i c.c. of the original normal acid have been concentrated to a 
volume of 10 c.c., which is equivalent to a concentration of the original 
15 c.c. employed to 13-51 c.c. 
Therefore, from the weight of water absorbed by the grain, a con- 
centration of the original 15 c.c. of normal acid to 13-19 c.c. has been 
found, and by direct titration a concentration of 13-51 c.c. — close agreement 
considering the relatively large errors present in the method of experiment 
which it was found necessary to adopt. 
In order to demonstrate still more conclusively that a solution of 
sulphuric acid is concentrated by the semi-permeable property of barley 
grains, four separate quantities of grain were steeped successively for 24 
hours each in the same solution of normal sulphuric acid in order to 
intensify the concentration effect. On subsequently titrating the acid 
solution which remained unabsorbed by the grain its strength was found to 
have increased from the original concentration of 4-9 per cent, to J-6 2 per 
cent. H 2 S 0 4 . 
The experiments described demonstrate conclusively that a separation 
of water and sulphuric acid is effected when undamaged grains of barley 
are steeped in solutions of sulphuric acid not exceeding a concentration of 
4-9 per cent. As it appeared desirable, however, to ascertain if a similar 
phenomenon is exhibited when barley grains are steeped in more con- 
centrated acid, some grains of the blue variety of H. vulgare were immersed 
in solutions of 9-0, 18-0, and 36-0 per cent. H 2 S 0 4 for 44 hours. 
On subsequent examination it was found in all the experiments that 
the original blue colour of the undamaged grains remained unchanged. 
Further examination by means of methyl-orange also demonstrated that 
no free acid had penetrated to the interior of the grains. When the grains 
G 
