150 HOW CROPS FEED. 
pass it. The apparatus being joined together, and the 
cock opened, the soil in 1 is agitated by the stream of wa- 
ter flowing through, and the finer portions are carried over 
into 2, 3, 4, and 5, Asa given amount of water requires 
eight times longer to pass through 2 than 1, its velocity 
of motion and buoyant power in the neck of 3 are corre- 
spondingly less. After the requisite amount of water has 
run from A, the cock is closed, the whole left to rest sev- 
eral hours, when the contents of the vessels are separately 
rinsed out into porcelain dishes, dried and weighed.* 
The contents of the several vessels are designated as 
follows :t 
1. Gravel, fragments of rock. 
2. Coarse sand, 
3. Fine sand. 
4, Finest or dust sand. 
5. Clayey substance or impalpable matter. 
In most inferior soils the gravel, the coarse sand, and 
the fine sand, are angular fragments of quartz, feldspar, 
amphibole, pyroxene, and mica, or of rocks consisting of 
these minerals. It is only these harder and less easily 
decomposable minerals that can resist the pulverizing 
agencies through which a large share of our soils have 
passed. In the more fertile soils, formed from sedimen- 
tary limestones and slates, the fragments of these strati- 
fied rocks occur as flat pebbles and rounded grains. 
The finest or dust-sand, when viewed under the micro- 
scope, is found to be the same rocks in a higher state of 
pulverization. 
* See, also, Wolff's ‘‘ Anleitung zur Untersuchung landwirthschaftlich-wichtiger 
Stoffe,” 186%, p. 5. 
+ These names, applied by Wolff to the results of washing the sedentary soils 
of Wirtemberg, do not always well apply to other soils. Thus Grouven, (8¢er Salz- 
minder Bericht, p. 32), operating on the alluvial soils of North Germany, desig- 
nated the contents of the 4th funnel as ‘‘clay and loam,” and those of the 5th 
vessel as ‘‘light clayand humus.” Again, Schéne found (Bulletin, etc., de Moscou, 
p. 402) by treatment of a certain soil in Nébel’s apparatus, 45 per cent of “‘ coarse 
sand’ remaining in the 2d funnel. The particles of this were for the most part 
smaller than 1-10th millimeter (1-250th inch), which certainly is not coarse sand t 
