THE QUESTION OF THE TOXICITY OF DISTILLED 
WATER * 
R. P. HiBBARD 
Introduction 
Attention has recently been drawn to the necessity of a physio- 
logically balanced salt solution for water cultures. This necessity 
arises from the fact that in order to know the effect on organisms 
of certain single salts or mixtures of salts in solution, one must use a 
control or check solution, called by True,^ a normal physiological 
solution. This solution or medium should cause no disturbance of 
the regular functions of the seedling. Such a culture would afford 
an ideal standard for comparison and one much to be desired. The 
usual method, however, has been to use distilled water. That such 
cultures for biological studies are unsuitable was shown some time 
ago. 
In the first place, * distilled water ' is an indefinite term. As soon 
as the seedling roots are introduced the conductivity of the water 
rises rapidly, showing that salts are leached from the roots and the 
water remains no longer pure. Secondly, the extraction of salts, it 
is affirmed, suggests the means by which pure samples of distilled 
water exert their harmful effects. Some authors affirm a starvation 
theory; others, like Loeb,^ the loss of certain necessary ion-proteid 
compounds; and still others, as True,^ that certain necessary con- 
stituents, partly inorganic, are dissociated from their proper attach- 
ments in the complicated chemical and physical mechanism of the 
living cell. Thirdly, the harmfulness of distilled water is attributed 
by others to the presence in it of toxic substance derived from the 
apparatus or because of the method of preparation. 
* Received for publication April lo. 
1 True, R. H. Distilled Water in the Laboratory. Science n. ser. 39: 296. 
1914. 
2 Loeb, J. On Ion-proteid Compounds and Their Role in the Mechanics of 
Life Phenomena. I. The Poisonous Character of a Pure NaCl Solution. Amer. 
Journ. Physiol. 3: 327. 1899-1900. 
3 True, R. H. The Harmful Action of Distilled Water. Amer. Journ. Bot. i: 
270. 1914. 
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