19. Homefire briquettes, manufactured by Coal Products Limited at Immingham Briquetting Works, Immingham, North East Lincolnshire, which—
(a)comprise anthracite fines (as to approximately 40 to 70 per cent of the total weight), petroleum coke (as to approximately 20 to 45 per cent of the total weight), char (as to approximately 0 to 10 per cent of the total weight), bituminous coal (as to approximately 5 to 30 per cent of the total weight) and an organic binder or a molasses and phosphoric acid binder (as to the remaining weight);
(b)were manufactured from those constituents by a process involving roll-pressing;
(c)have a volatile matter content in the finished briquette of neither less than 9 nor more than 15 per cent of the total weight on a dry basis;
(d)are unmarked hexagonal briquettes and have an average weight of 140 grammes; and
(e)have a sulphur content not exceeding 2 per cent of the total weight.