The bushel in struck measure shall contain twenty-one hundred fifty and forty-two hundredths cubic inches, and in heap measure twenty-five hundred sixty-four cubic inches, except that each bushel of charcoal shall contain twenty-seven hundred forty-eight cubic inches. When sold by weight, the bushel of charcoal shall weigh twenty pounds when commercially dry; the barrel of flour, one hundred ninety-six pounds, and the barrel of potatoes, one hundred fifty pounds.