118 THE CULTURE OF FARM CROPS. 



which, combined, form hydro-chloric acid ; commonly called 

 muriatic acid. This element fortunately does not exist in a 

 free state but is quite abundant in combination ; forming 60 

 per cent, of common salt ; (chloride of sodium). It is easily 

 produced by decomposing salt by means of the black oxide 

 of manganese, mixed with it, and placed in a bottle or jar 

 and pouring sulphuric acid upon the mixture. The chlo- 

 rine is separated from the salt and is given off in the form of 

 the gas described. It is a most characteristic element. It 

 extinguishes fire ; but it causes phosphorus ; gold (in the 

 form of "leaf"); potassium; sodium; and many other met- 

 als, to take fire when immersed in it, and burn ; combining 

 with them and forming chlorides. It is 4J times heavier 

 than air, and may be poured from one vessel to another. 

 Animals cannot breathe it, and when unmixed it destroys 

 all living vegetables. Yet its solution in water promotes 

 the germination of seeds. 



It exerts a strongly destructive effect upon organic matter, 

 and hence is employed as a disinfecting agent, to decompose 

 the noxious gases which emanate from putrid vegetable and 

 animal matter. It also quickly destroys colors, and on this 

 account is used for bleaching cotton goods. It is extensive- 

 ly distributed in nature as may be seen by its universal pres- 

 ence in the ash of plants, in some combined form. It is also 

 present in all the secretions and other fluids of animals, and 

 forms, as hydro-chloric acid, a portion of the gastric fluid of 

 the stomach. This acid is composed of chlorine and hy- 

 drogen. 



We have thus enumerated and described, as far as may 

 be useful, the inorganic elements of plants, and those parts 

 of the? which are derived from the soil. The nature of the 

 soil itself next claims our careful consideration. 



