2994 EW. Hilgard—Wilt analysis of Soils and Clays. 
The presence of clay in the instrument would materially in- 
terfere with the proper separation of sediments. In consequence 
of its property of indefinitely fine diffusion in water, clay—i. e, 
the hydrous silicate of alumina—produces the same effect as 
would the dissolution of a salt, viz: increases the buoyant 
effect, and therefore the hydraulic efficacy of water, to such an 
extent as to enable it to carry off, e. g., sediment pertaining to 
the velocity of 1™ in pure water, when the actual velocity is 
but 0-25™™. 
In view of these facts, I have adopted the following course 
of preliminary treatment : 
Boiling livelily, for 24 to 80 hours, 15 to 20 grams of 
weighed “fine earth.” 
This is best done in a thin, long-necked flask of about 1 
almost inevitably be decanted with the successive 
clay waters, until the buoyant effect of the clay becomes insel- 
sible. The united clay waters (of which there will be from four to 
ieee oy oreseen, some sediment of, and exceeding, 0 
° vV. Wi 
