E. W. Hilgard—Silt analysis of Soils and Clays. 298 
Ww 
time, as to render it by far preferable to so regulate the amount 
employed, that even the most copious sediments can be worked 
cpp bee the more concordant are the results. Between ten 
an 
cal separation. In no case have I found less than six hours 
incessant and lively boiling even approximately sufficient ; and 
even with double that time, so much of the disintegration 1s 
often left to be done by the churner of the instrument, as to 
protract indefinitely the exhaustion of the finer sediments, 
which are then continually being set free from the coarser por- 
i m 
after 12 hours boiling, the 0°25 sediment gave no sign of dis- 
appearance after 36 hours, and continued to come off for 54 
ours more, with the coarser sediments. : 
It is therefore a material saving of time, and essentially 
promotive of accuracy, to effect the mechanical disintegration 1D 
the most thorough manner, beforehand. is ca 
ime; the grains of bog ore, 0 ; 
found in some soils, fulfill, physically, the same office as solid 
sand-grains of corresponding size; and should appear as such 
m the analytical statement. 
