EFFECTS OF PULP MILL POLLUTION ON OYSTERS 145 
Table 1. — Experiments 2 and 3 and controls. Length of time specimens remained open as influenced 
by the presence of sulphite liquor. Liquor was started on October 23 — Continued 
EXPERIMENTS WITH NEUTRALIZED LIQUOR 
After sulphite liquor has been in sea water for some time the mixture ceases to 
give an acid reaction, due partially to neutralization by substances in the sea water 
and partially to loss of sulphur 
dioxide. It is necessary to be sure 
that, in the laboratory experiments, 
the effect of the liquor was not due 
to acid content. 
A series of experiments .was 
arranged to consist of 2 control 
oysters; 2 in a solution of 10 parts 
per thousand, and 2 in a solution 
of 5 parts per thousand of neutral- 
ized liquor in sea water. To the 
digester liquor was added concen- 
trated NaOH solution until the pH 
of sea water was not changed by 
addition of the liquor. The liquor 
was then allowed to set for from 12 to 24 hours t.o permit the precipitate, probably 
chiefly calcium sulphate, to settle. Then it was decanted and filtered through several 
layers of cheesecloth, which removed most, but not all, of the precipitate. 
Experiments Nos. 24 and 25 ( April 18 to May 8, 1980). — -Throughout the series, 
for either concentration employed, the pH of the solution in the experimental tanks 
did not vary more than 0.2 points from the pH of the control water (7.8). The 
temperature of the water varied from 10° to 15° C. 
Experiment No. 25 (10 parts per thousand). — The rate of flow of water was 103 
cubic centimeters per minute and that of liquor solution (1:4) was 5.1 cubic centi- 
meters per minute. Both oysters (fig. 28) were normally open and active when liquor 
Figure 28.— Records of oysters in experiment No. 25 (10 parts per 
1,000) in which neutralized sulphite liquor was used. Compare 
with the controls (fig. 29) which remained open >nd; normally active 
long after these were dead 
