Which preposition to use with offscouring

of Occurrences 24%

When the gold discoveries suddenly drew into the colony, not merely the most turbulent characters of Australia, but the crews of deserted ships and the general offscourings of the civilized world, and when, overcome by the contagion, the government officials threw up their posts, one and all, and started for the diggings, it became evident that the Lieutenant-Governor had his hands full.

Which preposition to use with  offscouring