COMBUSTION. 147 



delphia. The common arrangement 

 of this instrument is, however, repre- 

 sented in Fig. 62. In one reservoir 

 is the oxygen, and in the other the 

 hydrogen ; flexible tubes lead to a 

 common jet, where the gases issue 

 and are set on fire. The flame, not- 

 withstanding its heat, has very little 

 brightness. It melts almost all sub- 

 stances, even the most refractory, 

 dissipating many of them in vapor. 

 Platinum, which can not be melted 

 in the hottest furnace, readily melts Fig. 62. 



here. Most of the metals are oxidized as they bum in this 

 flame. Though the flame itself is so nearly colorless and 

 destitute of light, a dazzling light, variously colored, is pro- 

 duced as it burns the metals. Copper gives a beautiful 

 green light, and platinum a delicate white. The scintilla- 

 tions of iron are of a more dazzling brightness than when it 

 is burned in a jar of oxygen, as noticed in 59. 



189. Drummond Light. There are some of the earths, as 

 lime and magnesia, that resist the heat of the oxyhydrogen 

 blow-pipe, and one of these, lime, placed in the flame, gives 

 a light which rivals in brightness the noonday sun. An 

 arrangement having a burning jet of the two gases thrown 

 upon a ball of lime is called the Drummond Light, because 

 Lieutenant Druramond, of the English navy, if he did not 

 first discover the fact that such an intense light could be 

 thus produced, was at least the first to discover and recom- 

 mend its use for most of the purposes to which it is now 

 applied. The light can be seen at such great distances that 

 it is exceedingly useful for signaling. In one case the light 

 was seen at the distance of 70 miles. That a flame which 

 gives so little light of itself should be made so intensely 



