118 HOW CROPS GKOW. 



Exp. 20. Further account of them will be given undef 

 the metals. 



CHLORINE AND ITS COMPOUNDS. 



Chlorine, Sym. Cl, at. wt. 35.5. This element exists in 

 the free state as a greenish-yellow, suffocating gas, which 

 has a peculiar odor, and the property of bleaching vege 

 table colors. It is endowed with the most vigorous 

 affinities for many other elements, and hence is never met 

 with, naturally, in the free state. 



Sprengel claims to have found that Olaux maritirna and Snlicornla her- 

 baeea, plants growing in salt marshes, exhale chlorine. He says that the 

 chlorine thus evolved is very quickly converted into chlorhydric acid, 

 by acting on the vapor of water which exists in the atmosphere. Such 

 an exhalation of chlorine is manifestly impossible. The gas, were it 

 eliminated within the plant, would be consumed before it could escape 

 into the atmosphere. Chlorhydric acid is evolved from the mud of salt 

 marshes when left bare by ebb of the tide, and exposed to the heat of 

 the summer sun. It conies from the mutual decomposition of chloride 

 of magnesium and water, 



Mg Cl a + H a = Mg O + 2 H Cl. 



EXP. 55. Chlorine mtiy be prepared by heating a mixture of chlor- 

 hydiic acid and black oxide of manganese or red-lead. The gas being 

 nearly five times as heavy us common air, may be collected in gl;iss bot 

 tles by passing the tube which delivers it to the bottom of the receiving 

 vessel. Care must betaken not to inhale it, as it energetically attacks 

 the interior of the breathing passages, producing the disagreeable 

 symptoms of a cold. 



Chlorine dissolves in water, forming a yellow solution. 

 Very weak chlorine water was found by Humboldt to fa 

 cilitate the sprouting of seeds. 



In some form of combination chlorine is distributed over 

 the whole earth, and is never absent from the plant. 



The compounds of chlorine are termed chlorides, and 

 may be prepared, in most cases, by simply putting their 

 elements in contact, at ordinary or slightly elevated tem 

 peratures. 



Clilorliydric acid, also Ifydrochloric acid, Sym. H Cl, mo. wt. 

 3G.5. When Chlorine :ind Hydrogen gases are mingled together, they 

 slowly combine if exposed to diffused liti ht; but if placed in the sun 

 shine, ihcy tius.o explosively, and chloride of hydrogen or e.hlorhydiie 



