On the Continent the glass manufacturers usually grind and mix their fire-clays, with the result that they know exactly what they are using in making their pots and furnace goods, and they are not then dependent upon outside firms to carry out their wishes. English glass manufacturers usually buy their clays ready mixed, and as often as not have perforce to take the mixtures offered by the clay firms. Unfortunately, in Great Britain many of the firms who supply the refractory requirements of the glass trade are exceptionally backward in applying technical knowledge to their trade; consequently, progress is somewhat retarded in the glass trade as far as the refractory materials are concerned. So obstinate is this ignorance of science that quite recently one well-known firm replied to an inquiry for samples of fire-clays to be sent for important research work then being undertaken upon the resources of the country, stating “that, as their clay product was perfect, and research work was quite unnecessary.” It often turns out that their conservatism is simply a cloak to hide ignorance, as it is quite evident to any technicist that there is ample scope for improvement in the present goods on the market, and such an open opportunity for a scientific investigation into the nature of their fire-clays, however well known they may be, should be welcomed with delight, and every facility and assistance offered for research chemists to improve their material, and apply tests with the object of developing the best properties of such refractories for special purposes. ------------------------------------------------------------------------ CHAPTER VIII GLASS HOUSE FURNACES