A portion of the upper clear solution prepared by the above
method was filtered with the membrane (0.45 m) and preserved
in a weighted double dish which had been completely dried. The
double dish was quickly weighed to determine the mass of the sample.
The solvent in the double dish was completely evaporated after
10 h with the oven at 60 ◦C; the double dish was reweighed to determine
the mass of the residue solid and the evaporated solvent.