9. Briteheat briquettes, manufactured by Coal Products Limited, Immingham Briquetting Works, North East Lincolnshire, which—
(a)comprise anthracite (as to approximately 60 to 85 per cent of the total weight), petroleum coke (up to approximately 30 per cent of the total weight), bituminous coal (up to approximately 15 per cent 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 cushion-shaped briquettes with an indented line running longitudinally around the briquette;
(d)have an average weight of 30 grammes per briquette; and
(e)have a sulphur content not exceeding 2 per cent of the total weight.