in its Relations to Chemistrij and Geology. 
213 
arc they rare? Where are they likely to occur, and where not? 
Can we without actual trial say that any field will not exhibit 
them ? How would your own fields behave in this respect ? 
If you will carefully examine the various tables of experi- 
mental results which have been published during the last three 
years, you will find that in \e\-y few cases only has an answer 
been sought for or given to this last question. The natural dif- 
ferences in the unmanured crops of corn, roots, and hay, on 
different parts of the experimental field, have rarely been investi- 
gated. And even where, as in . some of the later series of expe- 
riments mcide at Barochan by Mr. Gardiner, two or more pieces 
of land were left undressed with a view to ascertain this point, 
the mean of the whole only is given, and the results of the 
manured portions compared with this mean. But it is the dif- 
ferences in the undressed portions themselves which it is desirable 
to know, as by them we are enabled to j udge how far the appli- 
cations we make to other portions of the same field have done 
good or harm. 
Take, for example, Mr. Chalmers's meadow already mentioned ; 
from one undressed portion of which he reaped 385 stones of hay 
and from the other only 281 stones per acre. The mean of these 
two is 333 stones. To one part of this field he applied 2 cwt. of 
gypsum per acre, and to another 4 bushels of bones dissolved in 
sulphuric acid, with the following results: — 
2 cwt. of gypsum gave . 287 stones per acre. 
4 bushels of bones dissolved 268 „ 
Mean of natural hay . . 333 „ 
If we were to compare these results with the wean of the un- 
dressed portions (333 stones), we should conclude that these 
dressings had diminished the crop in the one case 46, and in the 
other 65 stones per acre. If we compare them with the maximum 
produce of the natural hay, the diminution appears still greater; 
but such a result is preposterous and contrary to experience, and 
therefore it is satisfactory to find, upon comparing them with the 
minimum produce of natural hay (281 stones), that the dressed 
parts gave sensibly the same weight of crop. We find reason to 
believe that they did no harm, and it is rendered probable that 
they acted beneficially as usual. 
Second. But the same substance applied in the same quantity 
to different parts of the same field and crop produces differences 
of an equally marked character. 
Thus Mr. Dockar of Findon, on the same field of turnips 
spoken of above, obtained from two portions, to each of which 
bones at the rate of 20 bushels an acre were applied, the fol- 
lowing weights of bulbs per acre respectively : — 
