EFFECTS OF BLAST TEMPERATURES IN DRIVING FURNACES.
Hot blast is claimed to have been first introduced
by Mr. James Beaumont in Scotland in 1825. Up to this time cold blast only had been used. The use of hot blast has increased in temperatures from 100 to 1,500 degrees and higher. Every increase in temperature in blast was found to effect more or less of a saving in fuel and improve the working of a furnace up to 1,700 degrees; over this it has not proved economical. When only 100 degrees was used it proved to be an advantage over the cold blast. Then 200 degrees was used, showing better results than 100 degrees, followed by 300 and 400 degrees, and upward until a temperature of 1,000 degrees was obtained, which was as high as iron stoves or pipes would stand the heat without being rapidly burned away. The knowledge that every increase in temperature had proved beneficial gave confidence that a higher temperature than 1,000 degrees would prove still more economical, but in order to utilize a higher heat than 1,000 degrees, some other plan than '' iron stoves '' had to be devised. This improvement was not long in making its appearance. Different designs of stoves having all-brick .flues which could not be damaged to any radical degree were introduced with great success, and the tempera- L^,