SECT. r. NON-METALLIC SIMPLE SUBSTANCES. 19 



potassium, a salt is left which is the iodide of potas- 

 sium, whence iodine is obtained. Iodine is also found in 

 sponges, oysters, and other low sea animals, as well as in 

 certain mineral springs, and sometimes in combination 

 with silver. These three elemental bodies have little 

 affinity for one another, but they combine powerfully 

 with other substances. 



Chlorine is a yellowish-green gas, twice as heavy as 

 atmospheric air, with a noxious suffocating smell and 

 astringent taste. It has a powerful bleaching property, 

 and when combined with water, which absorbs twice its 

 volume of the gas, it is used for bleaching linen, in 

 calico-printing, and other arts. The clear solution of 

 chloride of lime is still more in use for the same purpose, 

 as well as for an antidote against contagion and un- 

 wholesome smells. Carbon does not burn in chlorine 

 gas, yet it is capable of supporting combustion, for oil 

 of turpentine, phosphorus, thin leaves of tin and copper, 

 and powdered antimony, take fire spontaneously in it. 

 This gas shows its power by the development of intense 

 heat, but not by briUiant light, because the results of 

 its combustion are mostly vapours, or such gases as 

 have a feeble illuminating power ; so chlorine differs 

 materially from oxygen in the phenomena of combus- 

 tion. Mr. Faraday observes, however, that the bleaching 

 powder is analogous to ozone in being an intermediate 

 state, for chlorine is pernicious and violently destructive 

 as a gas, perfectly innocuous and quiescent in common 

 salt and in its other natural combinations, while in the 

 bleaching substances its energy is subdued by art, so as 

 to make it an important agent in various manufactures. 



Providentially, chlorine is never found free ; but in a 

 combined state it exists in enormous quantities in the 

 salt of the ocean, in salt lakes, brine springs, and in 

 extensive deposits of rock-salt, as well as in organic 

 liquids. It has a strong affinity for hydrogen, and forms 



* c 2 



