33. Supacite briquettes, manufactured by Maxibrite Limited at Llantrisant, Rhondda Cynon Taff, which—
(a)comprise anthracite fines (as to approximately 84 per cent of the total weight), petroleum coke (as to approximately 12 per cent of the total weight) and starch as binder (as to the remaining weight);
(b)were manufactured from those constituents by a process involving roll-pressing and heat treatment at about 240° C;
(c)are unmarked ovoids and have an average weight of 45 grammes; and
(d)have a sulphur content not exceeding 2 per cent of the total weight.