10. Briteflame briquettes, manufactured by Maxibrite Limited, Mwyndy Industrial Estate, Llantrisant, Mid Glamorgan, which—
(a)comprise bituminous coal (as to 10 to 15 per cent of the total weight), petroleum coke (as to 10 to 15 per cent of the total weight), anthracite duff (as to 70 to 80 per cent of the total weight) and a starch binder (as to the remaining weight);
(b)were manufactured from those constituents by a process involving roll-pressing and heat treatment at about 260°C;
(c)are unmarked pillow-shaped briquettes;
(d)have an average weight of 140 grammes per briquette; and
(e)have a sulphur content not exceeding 1.9 per cent sulphur on a dry basis.