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any idea as to the actual amounts of interacting salts in the antago- 
nisms noted. For one thing, this would be impossible with the methods 
now possessed by soil investigators. Besides, we do not consider our 
results as applying to any phase of the problem except that of the actual 
conditions which exist in soils when certain amounts of the alkali salts 
are present, and when their effects are more or less modified by the 
addition of other salts. In view of these considerations, it appears 
that the question raised by us, in anticipation of its being brought 
forward by others, is of little pertinence in so far as our main thesis is 
concerned. 
Summary 
Experiments bearing on the antagonism between salts of the heavy 
metals, Cu and Zn, and the common alkali salts of soils have been 
carried out as follows: Plants were grown in pots and two different 
soils were tested. NaCl, Na2S04 and Na2C03 were used in toxic and 
constant quantities, the salts of the heavy metals varying in quantity 
within a given series. Barley was the plant grown. Briefly, the fol- 
lowing results were obtained : 
1. Copper and zinc antagonize NaCl, Na2S04 and Na2C03 in the 
Berkeley adobe soil, and the antagonism is evident even if three suc- 
cessive crops are used as criteria, and when only the metallic ions vary. 
2. When four ions are introduced, for example, as in the case of 
CUSO4 versus NaCl, fully as much and even more antagonism is 
manifest between the heavy metals and the alkali salts. 
3. Although only one crop was grown on the Oakley sand, similar 
evidences of marked antagonism between the heavy metals and the 
alkali salts were noted. The evidence in this case was, however, par- 
ticularly striking in the case of CUSO4 versus NaCl. 
4. These findings should possess considerable significance in the 
field reclamation of alkali lands, and particularly in the case of those 
which do not contain large enough quantities of salts to render them 
unfit for plant growth by reasons of high osmotic pressures in their 
soil solutions. 
