266 MORRIS S. FINE 
For the ‘methyl-orange alkalinity’ 5 ee. of infusion were titrated 
with 0.01 N HCl with methyl-orange as the indicator. As 
suggested by Peters,? the samples were titrated under xylol, thus 
retarding the loss of volatile matter during the process. In this 
manner was obtained the titratable acidity which, however, as 
Peters‘ points out, is probably not a correct expression of the con- 
in 
centration of H ions with which the organisms are in contact. 
For the third and fourth determinations recourse was had to 
methods employed in sanitary water analysis. To determine 
the oxygen consumed, 5 ce. of infusion, filtered clear, and diluted 
to 200 ec. with distilled water, were treated with 10 cc. of 50 per 
cent H.SO, and 0.01 N KMn0O,, the excess of the permanganate 
being titrated back with 0.01 N oxalic acid. For the chloride 
determination, 5 cc. infusion, filtered clear, were titrated with 
0.01 N AgNOs, using a solution of K, CrO, as an indicator. Total 
solids were obtained by evaporating 25 cc. of the filtered infusion 
to dryness. The residue was ignited, thus furnishing the data 
for the inorganic solids. The difference between these two last 
values is the solid organic matter. 
The three latter determinations are recorded in table 1. Infu- 
sion 2 suggests a general increase in oxidized material. The data, 
however, are scant and lack uniformity. The figures for the 
chlorides show a rise to a maximum with a subsequent fall. What 
significance, if any, may be placed upon these data it is impossible 
Oreee natlge indicate, as is to be expected, 
organic matter 
a general trend toward mineralized material. Of all the prelim- 
inary data, those for ‘phenolphthalein acidity’ appeared to be 
most characteristic and constant. Moreover this determination 
lent itself very readily to serial estimation. It was therefore 
planned to study this factor in considerable detail for a large 
number of infusions prepared in various ways. 
tosay. The ratios 
soc: cit., p. 463% 4 Loe. cit., p. 464. 
