CHEMICAL PROPERTIES OF HAY INFUSIONS 269 
Bacterial infusions. Eight infusions were prepared as follows: 
In each of eight cotton plugged flasks, 2.8 grams of hay and 700 cc. 
of water were placed and the mixtures sterilized in an autoclave. 
They were allowed to cool and were then treated in various ways: 
two were kept sterile; four were inoculated with a pure culture of 
B. coli; and two were inoculated with a pure culture of B. subtilis. 
On the foregoing cultures records were obtained for the ‘phenol- 
phthalein acidity’ and ‘methyl-orange alkalinity.’ In the ideal 
experiment, the temperature should have been maintained con- 
stant throughout the period during which the infusions were under 
observation; or, at least, all infusions should have been subjected 
to the same changes in temperature. Neither of these conditions 
could be conveniently brought about.? 
RESULTS 
The data secured in this study may be most readily presented 
by tables and curves. In tables 2, 3, 4, and 5 are recorded the 
results of the ‘phenolphthalein acidity’ and ‘methyl-orange alka- 
linity’ determinations, expressed in cubic centimeters of 0.01 N 
NaOH or 0.01 N HCl per 100 ce. of infusion. Peters has made the 
observation that the acidity becomes greater as the depth of the 
infusion increases and in order to give this quantitative expres- 
sion, titrations were made on samples taken from the bottom of 
the infusion at frequent intervals during its history. These 
results are given in italics immediately above the figures for the 
top, and are expressed as so many cubic centimeters of 0.01 N 
NaOH or 0.01 N HCl per 100 ce. of infusion greater (or less) 
than the titrations for samples taken from the top. The principal 
points of interest, brought out in these tables, are illustrated in 
figs. 1,2,3,and4. In calculating average curves only the ‘typical 
members’ of the three series were included. As a matter of fact, 
as far as the actual titrations are concerned, some of the ‘atypi- 
cal members’ might have been included, e.g., D-1, E-1 and 8-1 
9 For a discussion of the influence of temperature on these infusions, cf. Wood- 
ruff, loc. cit., p. 218 and also p. 274 of the present paper. 
