GAS AS A FUEL 



157 



2. The other type of burner is used with mantles made from 

 cloth dipped in thorium and cerium compounds. 



FIG. 127. Sewing. The fabric is now folded in at one end and carefully 

 plaited, and an asbestos cord drawn through to form the head and loop 

 of the mantle. Burning Out. The modelled fabric is then hung on a suit- 

 able hook and ignited at the top. The thread is burned out, leaving 

 an ash composed of the oxides of thorium and cerium. Hardening. After 

 the cotton is burned out, the soft, flabby ash is placed over a blow- 

 pipe, where the gas and air are controlled in such a way as to blow it 

 out to the form of a mantle. 



The mantle is heated to a glowing temperature by the burner 

 inside, which has sufficient air (oxygen) entering to produce a hot 

 colorless flame. 



In the first case, light is obtained 

 from the luminous carbon particles 

 in the flame. In the second type of 

 burner, light is obtained from the 

 luminous mantle, the flame itself 

 giving no light. 



The mantle gas burner has very 

 largely superseded the open flat 

 flame type of gas burner for use 

 in the general illumination of dwell- 

 ings, stores, factories, etc., because 



it produces from two to three times more light, and consumes on the 

 average only about one-half as much gas as the latter type of burner. 



FIG. 128. Modelling. After the 

 head is made, the saturated fabric 

 is shaped over a wooden form. 



