AMERICAN 
JOURNAL OF BOTANY 
Vol. I June, 1914 No. 6 
THE HARMFUL ACTION OF DISTILLED WATERS 
Rodney H. True 
Historical Introduction 
The use of distilled water in experimental biological work intro- 
duced a group of problems some of which still demand the attention 
of the investigator. The use of this medium was begun and has con- 
tinued because of the desire of the experimenter to test the effect of 
pure water, not only for the purpose of furnishing a check on the action 
of aqueous solutions of various substances under investigation, but 
also in order to meet the necessity of providing the pure substance 
for the study of the physiological action of water itself. 
It was early recognized that for chemical purposes distillation 
furnished a convenient means of ridding water of a great part of its 
impurities, and for many years distilled water was accepted as being 
pure water, and its effects were accepted as those characteristic of 
pure water. 
Harmful Action Recognized. — The essentially harmful action of 
distilled water was suspected, however, at a relatively early date by 
the plant physiologists, Sachs (i), Knop (2), Boehm (3), Deherain (4) 
and others. It was the general opinion that rain water, river water 
and water from other natural sources exerted a more favorable action 
on their experimental plants than distilled water and the use of natural 
waters was frequently resorted to in order to secure what was regarded 
as normal plant behavior. This harmful action was thought to be due 
chiefly to the lack of nutrients and less often to actively injurious 
qualities. 
At about the same time the deleterious effect of distilled water on 
^ Published by permission of the Secretary of Agriculture. 
[The Journal for May (i: 203-254) was issued 20 June 1914.] 
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