It shall be unlawful to sell at retail or offer for sale at retail any liquefied petroleum gas except by avoirdupois weight, specified in pounds or kilograms; liquid measure, specified in gallons or liters; or vapor, specified in cubic feet, cubic meters or such other units as may be approved by the secretary of agriculture.

L. 1951, ch. 331, § 1; L. 1996, ch. 146, § 4; April 18.