Place previously tared Gooch crucibles on filter manifold. Swirl beaker to suspend solids,and fill crucible. Do not admit vacuum until after crucible has been filled. Use low vacuum at-first and increase it only as more force is needed. Rinse sample into crucible with minimum of hot (90°-100° C.) water. Remove vacuum, break up mat, and fill crucible with hot water. Filter liquid and repeat washing procedure.