Mineral Manures and Manuring. 
279 
gauge is, however, at present very small. Thus, during the 
harvest year beginning September 1, 1879, and ending 
August 31, 1880, the rainfall was 21'358 inches, the season 
being the driest corresponding period in the past ten years. 
The drainage during these twelve months amounted to 6*890 
inches from the 20-inch gauge, to 7'393 inches from the 40-inch, 
and to G'495 inches from the 60-inch gauge ; the excess of 
evaporation on the GO-inch over that on the 20-inch gauge was 
thus only 0-395 inch. 
[To he continued.) 
XVIII. — Mineral Manures and Manuring. By H. voN LlEBiG, 
Munich. Translated and abridged by F. J. Lloyd, F.C.S. 
The increased facilities of transport which have arisen of late 
years, have materially diminished the value of many estates, and 
a large number of land proprietors have consequently suffered 
heavy losses. The imposition of protection duties, even sup- 
posing they were justifiable, would not have prevented this loss. 
Many soils, under the new conditions thus brought about, are 
really not fit for cultivation ; nevertheless they have to be culti- 
vated, because the large capital which has already been expended 
on them cannot be withdrawn. If they consist of light porous 
soils their possessors have but one means by which to protect 
themselves from impoverishment. It is by a judicious use of 
artificial manures. And this is also a sine qua non if we would 
protect ourselves against the competition of America, Russia, 
and the Balkans. 
The advice is still frequently given to plough an inch deeper 
in order to bring up new supplies of mineral food to the surface. 
It is founded on the supposition that the mineral food contained 
in the soil is inexhaustible and also easily dissolved. But as 
a matter of fact the subsoil is in 99 cases out of 100 much 
poorer in assimilable food than the surface soil. The roots of 
plants cannot make use of the potash in felspar, nor the phos- 
phoric acid in apatite. The carbonic acid in dung and the 
humus in the soil act far too slowly upon these minerals to 
dissolve a sufficient quantity of them for abundant crops, and 
ammonia is too expensive to be used as a solvent ; in fact, if 
farmers had to depend solely upon it there would be no prospect 
of a better future. 
This supposition of the inexhaustibility of the soil has proved 
a great hindrance to the application of mineral manures, as 
also has the belief that in order to raise the quality of the 
