52 CAN SODA REPLACE POTASH AS A MANURE. 
the sea. Only, in the former, the plant contains potash—the soda 
naving entirely disappeared. 
From these two examples, consequently, it would seem that potash 
can sometimes replace soda, without ill effects accruing from the sub- 
stitution. The mverse of this problem remains now to be considered : 
2.e., the question as to whether soda can be substituted for potash in 
certain, vegetables, and what may be the effects of this replacement. 
With regard to wheat, the answer is complete and peremptory. Soda 
employed to the total exclusion of potash, hinders most materially the 
development of the plant, and greatly lessens the amount of grain. 
In support of this assertion, I may cite two experiments, performed 
under different conditions, and confirmatory one of the other. 
A soil (that of the Landes) naturally free from potash, was employed 
iu these experiments. It was treated with 10 grammes of phosphate 
of lime, and 0.110 grm. of nitrogen—present, in the one case in 
nitrate of potash, and in the other in nitrate of soda. 
With phosphate of lime and nitrate of potash, an active and 
flourishing growth takes place. The wheat succeeds admirably: the 
stalks are firm, the ears well formed, and filled with large and heavy 
grains. 
On the other hand, when the nitrate of potash is replaced by nitrate 
of soda, the vegetation has quite another character: the growth is 
slow, the stalks incline in all directions, and the ears, when formed, con- 
tain but a few grains, and those of poor quality. 
These statements are confirmed by the following table, embodying 
the results of the experiments in question. The amount of wheat 
sown in each experiment was 20 grains. 
a B. 
Soil treated with phosphate of Soil treated with phosphate of 
lime and nitrate of potash : lime and nitrate of soda: 
Straw and roots.12er. at 14-92 Straw and roots...7g7.085 } 74] 
140 grains of wheat. 2er.78 "20 grains of wheat.0gr.325 ; 
The weight obtained in the first experiment, it will be observed, 
almost doubles that obtained in the second. Soda, consequently, 
cannot without detriment be substituted for potash. 
Another set of experiments was instituted by adding four grammes 
of silicate of potash to each of the mixtures described above. This 
had the effect of equalizing the results. The addition of the silicate 
