R.I. Gen. Laws § 5-4-7: Sale in units of less than 100 pounds.

Coal and coke of one hundred pounds (100 lbs.) or less per unit shall be sold in bags, baskets, or other vessels or receptacles; provided, that coal or coke shall not be sold or offered for sale in bags, baskets, vessels, or receptacles in units of less than eighteen pounds (18 lbs.). Those bags, baskets, vessels, or receptacles must be plainly marked in solid letters of not less than three-fourths (¾) of one inch in height, stating on them the weight of coal or coke that they contain and the name and address of the dealer putting up the coal or coke, together with the size and kind.