236 



Dr. W. M. Bayliss. 



[June 30, 



Notwithstanding these facts, it is undoubtedly remarkable that the osmotic 

 pressure of Congo-red solutions should correspond so closely to the " mole- 

 cular " through a very wide range of concentration. Table II gives a number 

 of experimental values corresponding to particular concentrations. In order 

 to obtain those of the higher concentrations, it was found necessary to 

 determine the difference between one of lower concentration outside the 

 membrane and one of higher concentration within it. The osmotic pressure 

 of the former was known from previous measurements. 



Table II. 



Conductivity in recip. ohms 



x 10°. 



Osmotic pressure in 

 mm. Hg. 



Inside. 



Outside. 



Difference. 



6220 



5070 



1150 



229 



5545 



5060 



485 



134 -7 



5033 



4335 



698 



176 



4360 



3130 



1230 



223 



3440 



2470 



970 



172 



'2498 



1762 



736 



122 



1762 



135 



1627 



245 



1670 



32 



1638 



263 -5 



1185 



20 



1165 



178 



705 



18 



687 



108 



409 



22 



387 



33(?) 



406 -5 



18 -75 



387 -75 



19 -5 



319 



146 -4 



172 -6 



27 -5 



277 -5 



21 "5 



256 



27 



205 



20 



185 



21 -3 



From these numbers a curve was constructed from which the osmotic 



pressure corresponding to any given conductivity could be obtained. From 

 the previous conductivity measurements of solutions of known dilution, the 

 dilutions corresponding to any given conductivity were known. 

 In Table III a series of such values are recorded. 



Table III. 



Conductivity in 

 recip. ohms x 10 8 . 



Dilution in 



Osmotic pressure 

 in mm. Hg. 



" Molecular " 

 osmotic pressure. 



Percentage 

 of " molecular " 

 found. 



6772 



14 



1220 



1328 



90 



5505 



18 



1020 



1032 



98 



3782 



28 



625 



664 



94 -5 



2086 



56 



326 



332 



98 



1154 



112 



176 



166 



106 



662 



224 



106 



83 



127 



367 



448 



45 



41 -5 



108 



201 



896 



24 



20 -8 



114 



All at 25° C. 



