524 Mr. W. C. M. Lewi- : Experimental Examination 
Experimental result : — 
250 c.c. of 0*1 per cent, Congo-red solution were shaken 
for fifteen hour- with * 1 7 5 c.e. of oil. The resulting; 
emulsion particles were examined under the microscope. It 
was found that r = -0000435 cm. 
Hence, calculating exactlv as in the sod. glvcocholate 
3 x '175 
solutions., we ohtain the Total adsorbing area = '.,..'. cm. g 
\ l\ M l\ i-±, ),J 
The quantity adsorbed was determined as usual by taking 
a drop-number with the pipette through the emulsion. The 
drop-number was found to be 158. = that is. a tension 
38*73 dynes cm., corresponding on fig. 5 to the concen- 
tration '082 per cent. 
.*. Fall in concentration = "045 grm. 
.*. Adsorption coefficient V = 3*7 X 10 ~ 6 grm. per cm.* 
It will be observed that this is very much the same value 
as was obtained in the case of the sod. glycocholate, and 
shows a large discrepancy as regards the calculated value. 
The fact, however, of a lowered tension shows that adsorption 
effects in the sense of Gibbs's theorv cannot be absent. 
Methyl Orange. 
The solubility of this substance in water 
saturated solution being about 0*073 per cent, 
ins results were obtained : — 
is small — a 
The follow- 
Table 
V. 
Per cent. 
Concentration. 
Drop- 
number. 
Kelative 
Tension. 
Tension in 
dynes/cm. 

12s 
10 
4S 
0018 
138 
927 
4449 
0-03K 
14o 
•892 
42-81 
0073 
152 
•842 
4041 
These values are plotted in fig. 5 (upper curve). 
It will be noted that fig. 5 has a marked difference in 
appearance to figs. 2 <k 3. This is of course due to the 
solubility limit being reached in the former case before the 
tension has fallen much in value. 
