44 
Thus the granitic waters, while quite rich in potash, do not contain 
any sensible amount of phosphoric acid. The volcanic waters, on the 
other hand, cantain less potash, but about one milligram of phosphoric 
acid per liter. The author concludes, from these analyses and compari- 
sons, that phosphoric acid is the principal element of the fertility of the 
soils mentioned, and that the volcanic soils owe their superiority in that 
respect, in a great measure, to the notable amount of that acid which 
they contain, which is rendered more easily soluble and assimilable by 
the presence of lime. 
NITROGEN AND AMMONIA IN BEETS.—Messrs. Champion & Pellet 
have published the results of an investigation upon the subject of the 
percentage of nitrogen and ammonia contained in beet-roots, from which 
they conclude: 
1. The soil and the percentage of nitrogen in the fertilizer employed 
being the same, the beets produced contain a larger percentage of 
nitrogen, according to the increase of the amount of sugar present. 
2. With like quantities of sugar present in the beets, the nitrogen in- 
creases with the increase of nitrogen in the fertilizer employed. 
3. The percentage of ammonia in the roots decreases with the increase 
of sugar. 
The authors further state that these conclusions also hold good for 
Sugar-cane. 
IRRIGATION.—The question of irrigation has lately received some 
valuable attention at the hands of Mons. A. Le Play, who has made the 
utilization of drainage-waters from springs and the superficial waters 
accumulated during heavy rain-storms a subject of special study. His 
object was, not only to utilize the water for the purposes of irrigation, 
but also to prevent excavation of ravines on inclined surfaces by removal 
of large quantities of soil by the immense accumulation of water during 
the storms. 
For this latter purpose he proposes to construct inexpensive trenches 
at regular intervals along the side of the hill, to collect the water at a 
given surface, to prevent an accumulation forming heavy streams, and 
to carry the water thus collected to the meadows requiring irrigation. 
The soil of the hill-sides, being composed principally of disintegrating 
and decomposing rocks, generally contains considerable quantities of 
lime, potassa, phosphoric acid, and nitrogen, and these matters, by 
the drainage and surface waters, may be distributed at will upon parts 
most needing them, while, if they be allowed to follow natural channels, 
they must be in great part lost in the lands of the immediate vicinity. 
Monsieur Le Play claims, asanadvantage of his mode of irrigation, that 
it avoids the possibility of close soils, the surfaces of which are consid- 
erably inclined, being cut up by large streams of water consequent upon 
heavy rains, and that therefore, independently of its importance in irri- 
gating meadows, it very materially facilitates the cultivation of moun- 
tainous regions. 
He conducted a series of analyses, the results of which, though form- 
ing a sound basis for his important deductions, have a local importance, ~ 
and are therefore not suitable for abstraction. They show, however, 
that the richness of the waters thus collected varies according to the 
season, the inclination of the soil, the conditions of culture, and espe- 
cially according to the conditions governing the system of manuring the 
fields through which they have to pass. He also found that the propor- 
tion of material of value as plant-food annually removed by water col- 
lected in these trenches, was far greater than could possibly be removed 
by the growth of different varieties of vegetation. 
