All gas furnished by any person engaged in the business of furnishing or supplying gas for heating, power or illuminating purposes in the city to any customer shall be and hereby is required to have a calorific value of not less than 800 British thermal units gross per cubic foot, as determined by a standard calorimeter measured at 60 degrees Fahrenheit and under a barometric pressure of 30 inches of mercury.
(Prior code § 187-3)