MANURING COFFEE. 201. 
504 bushels of wheat per acre. Nitrogenous manure 
without mineral matter, 18; without any manure, 12. 
Experience of a similar nature was uniform. The 
functions of clay, sand and humus as supports of 
plants are defined, and much importance is attached 
to clay as absorbing and giving out slowly nitrogenous 
and mineral matters. It resists the action of rain. 
Clay, therefore, if not excessive in quantity and stiff 
in quality, is a most valuable constituent of soils. 
The value of bumus consists in its power of absorb- 
ing moisture, and fixing the ammonia of the soils, so 
as to prevent it from being carried off by the rains. 
It afterwards gives back this ammonia to vegetation. 
It helps to form carbonic dioxide which exercises a 
solvent power, espevially on calcic phosphate and 
limestone. It was the result of his researches into 
the action of humus which led M. Ville to substitute 
calcic sulphate for the carbonate in the manufacture 
of normal manure. Cultivators in Ceylon cannot go. 
wrong, however, if they first treat clayey soils and 
fallen leaves, &e., to a good dose of burnt coral, and 
subsequently apply superohosphate potash and nitro- 
genous matter. M. Ville dwells on the frequent 
uselessness of soil analysis, because of the failure to 
distinguish solvent from nonsolvent matter. His own 
method of growing various plants in patches of soil, 
remedies this defect. But as such a method is im- 
practicable in the case of our culture, the analyst 
should either visit and carefully inspect in situ the 
soil he is to report on (by far the preferable plan), 
or the fullest possible information must be furnished 
when specimens of soils are sent for analysis. As a 
matter of much interest, however, we give M. Villes 
account of the process by which he uses plants as 
analysers of the soil. ‘* Plants are divided into two 
classes. With reference to the different forms under 
which they assimilate nitrogen—some obtaining 1 
from the air in the form of free nitrogen [leguminous 
plants, for instance.—EKp.], while others derive it from 
the soil in the form of ammonia and _ nitrates—you 
can appreciate the result of the distinction. Those 
plants which derive nitrogen from the air flourish 
exceedingly well in a soil which is destitute of that 
element, as long as they find in it the three mineral 
constituents of the normal manure, potash, calcic 
phosphate and lime. Plants which derive nitrogen 
from the soil become, on the contrary, etiolated and 
yield only a scanty crop. It follows from this that 
by the aid of two experiments on a small scale, we 
may always know if the land contains the necessary 
nitrogenous and mineral matter. 
