170 BOTANICAL GAZETTE [OCTOBER 
derived from OsTWALp’s dilution law, as explained in detail by 
THomAs (9). In this formula V =the volume in liters, in which one 
gram molecular weight of the substance is dissolved, and K =the 
dissociation constant. The values used for K are those given in 
SCUDDER’s (8) tables, and are for 25° C. 
The data from the acidity determinations, therefore, point to 
potassium binoxalate as the sole source of the acidity of the sorrel 
extracts, at least of those of the dried material. Furthermore, a 
calculation of the percentages of this salt present in the samples 
based on the titrable “acid” in the extracts of the dried leaves yields 
figures agreeing very closely with those obtained by DEvEt for the 
oxalate (as potassium binoxalate) dissolved by boiling water. 
These data, per se, do not preclude the possibility of the presence 
in the foliage of approximately equivalent quantities of free oxalic 
acid and normal potassium oxalate, which would simulate the acid 
salt, and, in fact, in aqueous solution would be identical with it. 
WHERRY’s observations on the dried material decides the point 
beyond a doubt. ‘The acid nature of the leaves is unquestionably 
due to the presence of potassium binoxalate. 
On recalculating the figures obtained for titrable acidity in the 
dried material (on which are based the figures for potassium binoxa- 
late in the leaves) to the original (green) moisture bases, it becomes 
apparent that there is a loss of titrable acid during the drying. 
These figures (footnote, table III) become 141.8 and 160.2 for 
“degrees of acidity” on the original bases, respectively equivalent 
to 1.82 and 2.05 per cent potassium binoxalate, while the acidity 
actually titrated in the fresh material yielded the figures 152.7 and 
185.4 (in terms of potassium binoxalate corresponding to 1.96 and 
2.38 per cent); therefore 10.9 and 25.2 cc. respectively of normal 
acid per kilogram of fresh leaves disappeared during the drying of 
the two samples. This lost “acid” may have been carbon dioxide 
or other weak volatile acids, or may be accounted for in part by 
changes in colloidal, acid-reacting protein. The discussion by 
ity of solution=0.0335 VN; hence V=29.85, K=4.9X10—5. Percentage ionization= 
3-75+- H per liter=0.0335X1.008 gm. H™ per liter=0.0375X0.0335 X1.008= 
0.001267 = 1.267 X10—3 .*. Pa=algebraic sum of —3, and log. 1.267=—2.897. Omit- 
ting the negative sign, Pa=2.9 (specific acidity = 12670). 
