JACQUES LOEB 



491 



It is obvious that the osmotic pressure in the curves for LiOH, 

 NaOH, KOH, and NH4OH (Figs. 2 to 5) reaches the same maximum 

 (at pH between 7.0 and 8.0), namely that of a column of about 325 

 mm. of a 1 per cent gelatin solution; and that the curves for osmotic 

 pressure of the Ca gelatinate and Ba gelatinate (Figs. 6 and 7) reach 

 also an equally definite maximum of about 125 mm. osmotic pressure 

 at about the same pH. In both cases we have probably to deduct 



300 

 275 



250 

 225 



200 



175 



150 



125 



100 



75 



50 



25 







pH 4.8 51 5.4 5.7 6.0 6.3 6.6 6.9 72 75 78 8.1 a4 



NH4OM 



Fig. 5. See explanation under Fig. 2. 



from these values about 25 mm.; namely, the osmotic pressure of a 1 

 per cent gelatin solution at the isoelectric point which includes the 

 necessary capillary correction. This then leaves the following char- 

 acteristic and constant values for the maximum osmotic pressure of 

 the two types of metal gelatinates: 



Li, Na,' K, NH4 gelatinate 300 mm. (uncorrected value 325 mm.) 



Ca and Ba gelatinate 100 " ( " " 125 " ) 



