VARIOUS PUOSFHATIC MANURES ON UPLAND SOIL. 
21 
From these results and our preceding explanations we may 
deduce the following conclusions : 
1. Of all phosphates applied, the double superphosphate was the 
most effective in the beginning, its rate of consumption by the 
first two crops cultivated in the first io months not being surpas¬ 
sed by any of the other fertilizers. After that time, however, its 
solubility diminished, probably because the dibasic compounds 
formed after its application are gradually converted into tribasic 
and polybasic ones, from which the phosphoric acid cannot be 
readily dissolved by the roots. It is, therefore, the best suited to 
crops of rapid development and to soils of medium absorptive 
power for phosphoric acid, and should be chiefly applied to crops 
cultivated in the spring or summer, a few days before sowing or 
transplanting. 
2. The precipitated calcium phosphate which in our case consist¬ 
ed chiefly of dicalcium phosphate mixed with some tricalcium 
phosphate was less active than the superphosphate, because its 
distribution in the upland soil cannot be accomplished to that ex¬ 
tent which is easily attained with the superphosphate. The 
monocalcium phosphate, the principal ingredient of the latter, 
dissolves in the fluids of the soil, and is then precipitated, thus 
assuming a state of extremely fine division, while the distribution 
of the precipitated calcium phosphate depends merely on the 
mechanical process of mixing. Though less rapid in the begin¬ 
ning, the action of the latter phosphate will usually continue 
longer than that of superphosphate. 
3. The three kinds of bone manure, steamed bone dust, crude 
bone dust and raw crushed bones gave very remarkable results. 
The first crop consumed from the steamed bone dust considerably 
more than from the two raw fertilizers, but the after-effect of the 
unrecovered phosphoric acid of the former was much inferior to 
that of the two latter manures. It must, however, be kept in mind 
that our specimen of steamed bone dust had been deprived of a 
part of its gelatinoid substance, which, during its decay in the 
soil, assists in the dissolution of the phosphatic ingredients of 
bones, and accelerates the action on crops. Had our steamed 
