BULLETIN OF THE BUSSEY INSTITUTION. 57 
If, as before, we refer the weights of the several crops to the weight 
of that with water as unity, the results will stand as follows : — 
Comparative yield 
ee Chemicals added to the pit-sand. on ape teats 
alone = 1, 
10 ; Nitrate of lime, sulphate of magnesia, and phos- 30.46 
phate of potash ; ‘ 
11 1 Nitrate of lime, nitrate of ‘potash, sulphate of t 97.01 
magnesia, phosyfhate of potash . alps 7 
8 Nitrate of lime and phosphate of ge ths et 26.38 
3 Nitrate oflime . . Cae 24.62 
4 Nitrate of potash and sulphate of magnesia i ie 22.85 
1 Nitrate of potash . . lite PR po hire ea, 21.64 
6 SMREOAINIOVIUA, 5 sw ot ww es 16.53 
2 MUU AGAENNEKIA'. ee ks 5.54 
7 Phosphate of potash ui s : 5.00 
9 Sulphate of A Rice and I phosphate of potash ; 2.23 
5 Rain-water . . ‘ oh 0 
These results were somewhat unexpected. They indicate clearly 
that the thousand grammes of sand gave up to the plants more potash 
and phosphoric acid than the five hundred and twenty-five grammes 
of coal-ashes did ; though we are left in some doubt as to whether the 
sand is absolutely superior to the ashes, weight for weight. It may 
be that the better effect produced by the sand, as compared with the 
ashes, is due to the fact that a larger amount of it was employed. It 
is true, moreover, that the comparatively coarse and incoherent sand 
affords better standing-room for plants than ashes can. The tender 
rootlets push their way through the sand in all directions more readily 
than is possible in the comparatively compact ashes. 
It is plain, however, from the foregoing trials, that no general answer 
can be made to the question whether coal-ashes possess more fertiliz- 
ing power than sand. For, inasmuch as the experiments prove that 
the coal-ashes examined were no better than a sample of pit-sand, of 
nearly equal bulk, selected at random, the question as to the relative 
merit of ashes and sand necessarily becomes a special one, which must 
be asked afresh for the sand of each new locality, and which can be 
answered only by experiments made upon each particular sand. The 
fact remains, however, no less interesting than remarkable, that an 
average sample of the apparently sterile silicious sand of this vicinity 
has been found to contain appreciable quantities of potash and phos- 
phoric acid in a condition fit to be taken up by plants on the addition 
VOL. I. 8 
