52. Jewel briquettes, manufactured by Eldon Colliery Limited at Newfield Works, Bishop Auckland, County Durham, which—
(a)comprise anthracite (as to approximately 30 to 50% of the total weight), Long Beach petroleum coke (as to approximately 50 to 70% of the total weight) and a carbohydrate binder (as to the remaining weight);
(b)were manufactured from those constituents by a process involving roll-pressing and heat treatment at about 150°C;
(c)are unmarked pillow-shaped briquettes;
(d)have an average weight of 33 grams; and
(e)have a sulphur content not exceeding 1.5% of the total weight.