i. SOURCES. 25a 



cast steel in 25 minutes. With a f bore gas-pipe the furnace can be con- 

 structed to give the same results in half the time, and so on in proportion, the 

 power being limited only by the gas supply and the fusibility of the refractory 

 clay jacket. A small foot blower only is necessary to create a current of air 

 in the burner tube, the jet of air from the blower acting as an injector, and 

 drawing in the air required for combustion from the atmosphere. By closing 

 the air slide to a greater or less extent the same burner acts equally well in 

 proportion with any gas supply from 10 cubic feet per hour. The texture of 

 the refractory casing is cellular throughout, and the loss of heat by radiation 

 is practically nil. 



988. Low Temperature Gas Burner, to dispense with 

 drying closets, sand and water baths, and adapted for drying, 

 evaporating, boiling, &c. Thomas Fletcher. 



This burner gives a range of temperature from a gentle current of warm air 

 without visible flame to clear red heat, and is so perfectly under control that 

 a common glass bottle may be placed on tripod, and heated to required 

 temperature, without risk of fracture. 



For very low temperatures, the ring must be lighted through the lowest 

 opening. This gives a steady current of heated air through the gauze above 

 For boiling, &c., a light must be applied on the surface of the gauze, thereby 

 providing a large body of blue flame, which can be urged by the blast-pipe 

 until it gives a clear red heat. 



989. Hot Blast Blowpipe, for temperatures up to the 

 fusion of platinum. Thomas Fletcher. 



The air jet in the above is coiled round the gas pipe in a spiral form, and 

 both are heated by three Bunsen burners underneath, which are controlled 

 by a separate tap. By this arrangement the power is double that of the 

 ordinary blow-pipe. When the jet is turned down to a small point of flame 

 it will readily fuse moderately thick platinum wire. 



990. Gas Crucible Furnace, for temperatures up to white 

 heat, and requiring neither blast nor attention. Thomas Fletcher* 



991. Gas Muffle Furnace, requiring neither blast nor 

 attention ; for temperatures up to fusing point of cast iron. 



Thomas Fletcher* 



992. Diagram of the Porcelain Furnace at Sevres, 

 part of it being open to show the interior construction. Painted 

 by Mr. Hubertus Sattler. 



Dr. Alexander Bauer, Professor, Polytechnic Institute^ 

 Vienna. 



993. Diagram of the Bottom of a Blast Furnace for 

 Smelting Iron. 



, Dr. Alexander Baiter , Professor, Polytechnic Institute + 

 Vienna. 



995. Gas Furnaces. Perrot System. 



Geneva Association for the Construction of Scientific In- 

 struments. 



