Quick Sand. Bl 
and soils for the reason that thin particles adhere to each other 
with less tenacity. Indeed it would he very difficult to commu- 
nicate to a whole hed of marl or clay, in place — as to a bed of 
sand — this partj^ally fluid state ; because the parts adheie togeth- 
er with so much force that they will not pcimit more water to 
enter than is sufficient to saturate them; or to fill the interstices, 
or space between thin particles. But when this adhesion is bro- 
ken down by mechanical agency the mass will become partially 
fluid like sand under similar conditions; but not as difficult to 
control. The less adhesion there is between the particles — other 
circumstances being the same — the greater will be their mobility. 
It will be seen from the experiments on the quantity of water 
which soils are susceptible of taking up, that sands sank the low- 
est — that it requires nearly twice the quantity of water to saturate 
clay, — three times the quantity to saturate marl, and four times the 
quantity to saturate sand. Hence, throwing the tenacity of the 
parts out of the question, and reducing all to the same state of de- 
composition and fineness, and subjecting them to the same or sim- 
ilar conditions, the sand would be twice as likely as the clay, 
three times as likely as the marl, and four times as likely as 
the peat, to assume a partially fluid form. Much greater is their 
difference when viewed as they ordinarily occur. 
All that is necessary to make a sand bed what is commonly de- 
nominated a bed of quick sand, is more water in its mass than it 
can absorb. The same thing may be said of beds of clay, marl 
and soils. 
Stiff clays saturated with moisture are nearly, though they can- 
not be said to be entirely, impervious to water, for if water be in 
contact with clay, and the clay be placed between an absorbing 
surface and the water, the water will pass through the clay to the 
absorbing body; but as a general thing it will not permit — with- 
out the aid of some mechanical force — more water to enter than 
is sufficient to saturate it. But if it could be subjected to condi- 
tions where after the mass being saturated, water could be made 
to enter with a force sufficient to break down the adhesion of the 
parts, then the particles would be made to recede from each oth- 
6 
