26o 
RODNEY H. TRUE 
grown in containers in which considerable areas of pure platinum 
metal were allowed to remain throughout the duration of the experi- 
ment showed a greater growth after 1 1 days than did the roots in the 
control culture of distilled water. Copper is here the most harmful. 
During the second 24-hour period, no clear advantage seems to lie 
with any kind of material. The cause of damage present in all of 
these distilled waters continues to operate throughout the period of the 
experiment. 
In view of the harmful action of the water distilled from glass, it 
seems to follow that metal carried over from the apparatus can hardly 
be invoked as the fundamental source of trouble. 
Effect of Distillation Process Compared with Freezing Out 
It being clear that all waters purified by distillation were harmful 
compared with tap water, the question next arose as to whether the 
process of distillation itself, in the various kinds of apparatus used, 
was the source of trouble, or wtiether water purified by other means 
would act like distilled water. Accordingly, clear, natural ice was 
melted and refrozen three times in vessels containing no metal, the water 
not being allowed to warm to room temperature until after the last 
recrystallization. Comparison cultures of distilled water condensed 
in copper and platinum and a check in Potomac water were set up. 
Table II 
Waters Purified by Distillation and by Recrystallization 
Growth ist Growth 2d 
Method of purification 24 hrs., mm. 24 hrs., mm. 
Recrystallization 13.0 5.0 
Copper condensed 15.0 7.5 
Platinum condensed 15.0 6.4 
Potomac water 20.7 17.0 
It appears from these results that water purified by repeated re- 
crystallization is fully as harmful to lupine roots as that purified by 
distillation. This result suggests two explanations of the cause of 
trouble — either the water is harmful because of traces of toxic sub- 
stances left in it by both the recrystallization and the distillation pro- 
cesses, or it is more harmful than in its original state because of the 
loss of substances there present. 
