THE GLASS INDUSTRY. 583 



any interruption to the flow, a coal fire could be started in six 

 or eight minutes. In the glass furnaces themselves greater 

 changes were necessarily made. As the supply of gas became 

 more abundant and assured, the tendency was toward the evolu- 

 tion of distinct apparatus for its utilization. At the present 

 time the glass furnaces burning natural gas are models of sim- 

 plicity and efficiency. In the melting furnaces the gas is admit- 

 ted at each end of the furnace and mixes with air which has 

 previously been heated by passing through flues in the brickwork. 

 The combustion thus takes place in the melting chamber directly 

 above the crucible pots, and produces an intense and easily regu- 

 lated heat. The blowing furnaces are even simpler. They merely 

 provide a chamber of brickwork with suitable openings in the 

 sides, and immediately under each opening a large Bunsen burner 

 supplied with natural gas and drawing the requisite air directly 

 from the atmosphere. 



Under the stimulus of the new fuel the development of the 

 glass industry since 1885 has been without precedent. The great- 

 est growth took place first in the flint-glass works, because in 

 these the advantages of the gas were most manifest. The absence 

 of coal smoke and dust, and the tendency to reduce the lead oxide 

 to the metallic state, were in themselves sufficient to bring about 

 the substitution of the gas for the coal, had there been no other 

 reasons. But the economic advantage was also in favor of gas. 

 Thus, a factory which was run by coal in 1883 at a weekly cost 

 of $175.17 was operated by natural gas in 1885 for $94.96, effect- 

 ing a saving of forty-six per cent. In addition to this the repairs 

 were less costly and the product was more salable. 



The introduction of natural gas into window-glass factories 

 was held for some reason to be less advantageous than in 

 flint-glass works, but the tradition rapidly melted away in the 

 face of a larger experience. By 1885 and 1886 natural gas had 

 made its way into all departments of glass-making, and every- 

 where turned out to be an immense improvement. Now it 

 is the universal fuel, and up to the present year it has been 

 the cause of that concentration of the industry of which we 

 have already spoken. It has not only given a better product 

 and more economic working, but it has made possible the carry- 

 ing out of operations on a scale hitherto undreamed of. In 

 plate glass and window glass the product is now measured by 

 the acre, and even by the square mile, where formerly it was 

 reckoned in feet. Hollow ware is shipped by the ton in place 

 of pound lots. One hundred and twenty thousand dozen lantern 

 globes are turned out as a summer's work. With the more 

 complete organization of the industry it is no longer necessary 

 for large plants to grow out of small ones. The conditions need- 



