In regard to the constituents of the ash, potassium is by far the most abundant-the oxide averaging about 50 per cent.
"Studies of American Fungi. Mushrooms, Edible, Poisonous, etc."
George Francis Atkinson
It is covered with a thick black pellicle of the magnetic oxide of iron, except at the point where it first struck the ground.
"The Story of the Heavens"
Robert Stawell Ball
These globules contain a certain quantity of iron, which from chemical tests is inferred to be in the state of oxide.
"A System Of Logic, Ratiocinative And Inductive (Vol. 1 of 2)"
John Stuart Mill