336 E. W. Hilgard—Silt analysis of Soils and Clays. 
evaporate the last 25-50 ¢.c.m. in the platinum dish in which it 
is to be weighed. 
From the other sediments, the water may be decanted so 
e 
to elutriation, as proposed by some, is obviously inadmissible, 
as it would render impossible the separation of the clay from 
the finer sedimen 
regions, than that of the surface soils, which are much more 
liable to local “ freaks and accidents,” and usually differ from 
the corresponding subsoils in about the same general points. 
For practical purposes, therefore, the difficulties incident to the 
be avoided. 
cause almost universally present, material for refere 
m 
ment, and tu scale divisions of ;4, millimeter each. ae 
As a matter of course, all sizes between that given and the 
one next below are to be found in each sediment. A few 
grains of the finer sediments are also invariably present, owing 
both to the progressive disintegration of conglomerated yin 
cles by the stirrer, and to the inevitable formation ok ae 
the scientific observer, it seems desirable to attach rox: 
esices, generally intelligible designations, which shall a) al 
imately, at least, indicate the nature of the s ieee 
have attempted in the table, which is in this respect, © ecg 
+ This Journal, Dec., 1872; Proc, Am. Assoc. Adv. Sci., 1872, p. 1 
