ASHES. 129 



lend us an old kitchen plate, and burn our magnesium over 

 that." 



This was accordingly done. The landlady, when the 

 table was cleared, brought in a plate. John broke off 

 about an inch in length from the end of his little ribbon 

 of magnesium, and for a handle he used a match, first 

 breaking off the phosphoric end, and then making a little 

 cleft with his pocket knife in the wood, by which means 

 he formed a kind of extemporized forceps to hold the mag- 

 nesium. When all was ready, Lawrence lighted another 

 match and set the end of the magnesium on fire, while 

 John held it over the plate. It kindled with some difficul- 

 ty, as if the end of the metal required to be raised to a 

 great heat before the process of combining with the oxy- 

 gen of the air could begin ; but, when it was once begun, it 

 went on with a very intense action, producing a light so 

 vivid and dazzling that it was almost impossible to look 

 at it. 



The piece of magnesium which was burnt was very short, 

 and it was, moreover, very narrow and exceedingly thin, 

 so that it was soon expended. John uttered some excla- 

 mations of delight while the burning was going on, and 

 when it went out he looked attentively at what Avas left. 

 It was a white substance of exactly the same form with 

 the little ribbon of magnesium, but, on touching it, it fell 

 to an impalpable powder. 



" What white ashes !" said John. 



" No," replied Lawrence, " that is not properly ashes at 

 all. The ashes left in burning wood are not produced by 

 tiie combustion, but only left by it. The substances which 

 are produced by the combustion in the case of wood go off 

 into the air as gases; the ash is only the incombustible 

 substance that is left behind. But the white powder in 

 this case is formed by the combustion that is, it is com- 

 F2 



