Stiles and J ergensen. — Studies in Permeability . V. 429 
would depend on the dilution of the acid, followed by a shrinkage which 
would appear sooner the stronger the solution. 
. N 
Fig. 9 shows that this is the case. With — sulphuric acid the maximum 
N 
swelling is reached in an hour, and with acid as dilute as the tissue 
begins to shrink after four hours’ immersion. 
N 
acid by the sixth hour of immersion, and even 
2,000 
about shrinkage before the elapse of twenty-four hours. 
It will be observed that in the 
lower strengths of sulphuric acid the 
swelling is at first actually greater than 
in distilled water. It is possible that 
this may be referred to the well-known 
phenomenon of increased swelling of 
proteins in acid solutions as compared 
with pure water, a phenomenon on 
which much stress has been laid by 
Fischer ( 7 ), who successfully shows the 
similarity between the swelling of such 
proteins as gelatine and blood-fibrin 
with certain animal tissues, frog’s muscle 
and sheep’s eyes. 
The observed increased swelling of 
potato in dilute acid solutions appears 
to be a definite increase and not merely 
due to variations in the samples, as 
the differences are for the most part 
considerably greater than the probable 
error. These are given in Table X. 
1,000 
Shrinkage was observed in 
^ acid brought 
5,000 
Fig. 9. Curves illustrating influence of 
different concentrations of sulphuric acid on 
the swelling of potato. 
Table X. 
Swelling of Potato in Various Concentrations of Sulphuric Acid . 
Distilled Water. 
N 
5,000 
h 2 so, 
N 
2,000 
H^SO k 
N 
1,000 
H 2 S0 4 
N 
5 ° 
H 2 SO A 
Time. 
Swelling. 
Time. 
Swelling. 
Time. 
Swelling. 
Time. 
Swelling. 
Time. 
Swelling. 
hrs. 
per cent. 
hrs. 
per cent. 
hrs. 
per cent. 
hrs. 
per cent. 
hrs. 
per cent. 
0-50 
4.0 + 0*05 
0*58 
5 * 7 ±o *2 
0-50 
4*5 ±°*° 
0*50 
4* 3 ±o*o 
0-25 
0*37 
2*00 
9.410-3 
2*23 
10*7 + 0*25 
2*17 
9*9 + 0*2 
2*00 
9 ' 5±°‘ 2 5 
1-02 
o *53 
3*60 
1 1*2 ±0*4 
3*6 7 
12*8 + 0*3 
3-63 
12*1+0*15 
3 *r 8 
10-0 + 0*3 
2*52 
— 0*40 
5*85 
1 2.7 + 0*35 
5*88 
i 4 *o±o *35 
5*87 
11*8 + 0-25 
5*88 
7 * 3 ±o *25 
3*32 
— 1*16 
7*oo 
I 3 , 5±° , 3 
7*05 
14*8 + 0*25 
7.03 
1 1*4 + 0*25 
7*00 
5*i ±0*4 
4-37 
-i *59 
21*90 
I 7 , 4±° ,I 5 
24*18 
I 3 '°± 0 ' 1 
24.78 
2*6 + 0*4 
24*20 ■ 
— 7 * 5 ± I *3 
Gg 2 
