Before beginning this season, the walls of the building had been given a coat of whitewash, and now a wood fire must not be lit anywhere near the premises, for the precious olive oil might take a smoky taste.
It was therefore with great wrath that Delpha, who was careful to obey rules, found one day, in a crushing trough under her supervision, some scattered little pieces of iron.

Now iron must never be allowed to come in contact with olive juice.

The tannic acid in the olive juice acts very rapidly on the iron, producing a kind of ink, that turns the oil black and almost ruins it.

The American's crushing troughs and weights were of granite.

Delpha was sure Sara had scattered the pieces of iron in the crushing trough on purpose to bring Delpha into trouble.
"I do something to her!" resolved Delpha fiercely.