316 



LETTERS ON NATURAL MAGIC. 



fire to gas. In this case the minutely divided 

 platinum acted upon the hydrogen gas in the 

 same manner as the minutely divided charcoal 

 acted upon common air. Heat and combustion 

 were produced by the absorption of both gases, 

 though in the one case the effect was instantane- 

 ous, and in the other was the result of a 

 prolonged absorption. 



This beautiful property of spongy platinum was 

 happily applied to the construction of lamps for 

 producing an instantaneous light. The form 

 given to the lamp by Mr. Garden of London is 

 shown in the annexed figure, where AB is a globe 

 Fig. 78. 



of glass, fitting tightly into another glass globe 

 CD by a ground shoulder m n. The globe AB 

 terminates in a hollow tapering neck m n o p, on 

 the lower end of which is placed a small cylinder 



