Weigh to the nearest tenth of a gram a wide-mouthed flask of 100 to 300
cc. capacity, according to the quantity of material available. Then
completely fill the flask with distilled water to the brim and weigh it
again. Empty the flask and fill it completely with fresh sewage sludge
or mud. If the material is of such consistency that it flows readily
fill the flask to the brim and weigh. The specific gravity is equal to
the weight of the sludge or mud divided by the weight of an equal volume
of distilled water.
If the material does not flow readily fill the weighed flask as
completely as possible without exerting pressure during the procedure.
Weigh and then fill the flask to the brim with distilled water. Let it
stand for a few minutes, until trapped air has escaped, then add more
water if necessary and weigh. Subtract the weight of the added water
from the weight of the water that completely fills the flask; the
specific gravity is equal to the weight of the material divided by this
difference. Record the specific gravity only to the second decimal
place.