33. Phurnacite briquettes, manufactured by Coal Products Limited at Immingham Briquetting Works, Immingham, North East Lincolnshire, which—
(a)comprise anthracite duff (as to approximately 65 to 85% of the total weight), petroleum coke (as to approximately 20% of the total weight) and a molasses and phosphoric acid binder (as to the remaining weight);
(b)were manufactured from those constituents by a process involving roll-pressing and heat treatment at about 300°C;
(c)are ovoid-shaped briquettes with two parallel indented lines running longitudinally around the briquette;
(d)have an average weight of 40 grams per briquette; and
(e)have a sulphur content not exceeding 2% of the total weight.