154 



S CIO PT ICON MANUAL. 



While the amount of the alcohol flame depends on the 

 height of the fountain, this flame is easily regulated by 

 the hydrogen key to the exact amount 

 required by the oxygen. 



The oxygen, shooting up like the 

 middle arrow from the 'flat-mouthed jet, 

 o (see its shape, front view, Fig. 39), 

 combines with the hydrogen instanta- 

 neously as it strikes the lime, with little 

 tendency to cool and blacken a central 

 spot. 



THE I>R17MJIOM> LIGHT. 



Lime rendered incandescent by the 

 * ignited jet of an oxy-hydrogcn blow- 

 pipe, invented by Dr. Hare, of Phila- 

 delphia, and used with marked success 

 in the British Signal Service, by Lieut- 

 Drummond, has been called the Drum- 



No. 2, Fig. 38. ^Ond Light. 



This term applies distinctively when 

 a collected supply of hydrogen gas, as well as of oxygen, 

 is required, and when both are alike under heavy pres- 

 sure and forced through the tubes of the blow-pipe. 



Oxygen and hydrogen, mixed in a common reservoir, 

 cannot be safely used in connection with an ignited jet. 



The separate gases, however, may be forced upon 

 the lime through entirely separate jets, in accordance 

 with the primitive arrangement; or, which amounts to 

 about the same in effect, the two currents may terminate 

 in tubes one within the other, called the concentricjet, 

 mingling as before only when projected upon the lime; 

 or, which is counted the most effective and is now in 

 general use, the oxygen and hydrogen may be mixed in 



