COPPER AND ZINC AS ANTAGONISTIC TO " ALKALI " SALTS 1 57 
the effect is relatively slight. The antagonism is most marked in the 
first and third crops at concentrations of CUSO4 in excess of 300 parts 
per million, while in the second crop it is just as marked at 100 parts 
per million as at 200 and 300 parts per million and much more marked 
than at the higher concentrations. 
Root yields seem to have been definitely improved by the antagon- 
istic influence of CuSO^ to Na2S04 in the first crop. In the second 
crop, the effect was barely perceptible at the higher concentrations of 
CUSO4 employed, but it was again clearly evident in the third crop, 
despite the poor agreement between some of the yields of the duplicate 
pots. 
Series II 
CuCl2 versus NaCl — Adobe Soil. 
NaCl .3 percent constant — CuCU varying. 
As was the case in Series I, three consecutive crops were grown and 
harvested in this series. The antagonism between Cu and Na seem 
to be very much more marked, however, in Series II than in Series I. 
The results obtained are given in Tables IV, V, and VI, for the first, 
second, and third crops, respectively. 
As regards straw production in the first crop, increases in yield, 
due to the antagonistic effect of CuCU to NaCl, rise to a maximum of 
75 percent over that obtained in the pots treated with NaCl alone. 
Small additions of 50 to 100 parts per million of CuCl2 seem to have just 
as strong an antagonizing influence as larger applications of that salt. 
Additions of CuCU, equivalent to 300 or 350 parts per million, still show 
as high antagonizing powers as the smaller amounts. Additions of 
larger concentrations of CuCl2, however, do not show an antagonizing 
power; but, even up to and including concentrations of 500 parts per 
million CuCU, they do not increase the toxicity of .3 per cent. NaCl. 
Higher concentrations of CuCU than 500 parts per million were not 
tested. In the second crop, straw production, owing to the unfavor- 
able conditions for growth at the time, was unsatisfactory, but shows 
clearly enough the antagonism between CuCh and NaCl at nearly all 
concentrations used. This was true, moreover, despite the fact that the 
toxicity of .3 percent NaCl was scarcely manifest, due apparently to the 
general poor growing conditions for the crop. In the third crop, the 
antagonism as regards the straw yields is very marked. The toxicity 
of NaCl, as shown in Table VI, reduces the yield of barley below that in 
