328 DISTRIBUTION OF ELEMENTS. 



and ir is not uncommon in tlie mineral. Sulphur is 

 common to the three kingdoms: it is abundant in the 

 mineral^ being one of the products of volcanic action ; 

 it is united with the metals, forming sulphurets; and is 

 foilud in our rocks in the state of sulphuric acid or 

 oxidi/ed vapour, combined with the metallic bases of 

 lime uuil other earths. In the vegetable kingdom we 

 discover sulphur in all plants of the onion kind, in the 

 mustard, and some others ; it enters into the composition 

 of vegetable albumen, and appears always combined with 

 albumen, fibrine, and caseine, in the animal economy. 



Chlorine is found most abundantly in combination 

 with sodium, as common salt : in this state, in par- 

 ticular, we may trace it from the depths of the earth, its 

 waters, and its rocks, to the plants and animals of the 

 surface. Iodine is most abundant in marine plants ; 

 but it has been found in the mineral world, traced to 

 plants, and it is indicated in the flesh of some animals. 

 Bromine is known to us as a product of certain saline 

 waters, and a few specimens of natural bromide of silver 

 have been examined. Fluorine, the base of the acid 

 which. Combining with lime, forms fluor-spar, is found 

 to exist to some considerable extent in bones ; it has 

 been discovered in milk and blood; and investigations 

 have proved its existence in the vegetable world. It 

 must not be forgotten that the earths, lime and mag- 

 nesia, ^nter into the composition of the more solid parts 

 of iplants and animals. Lime is one of the principal 

 constituents of animal bone and shells, and it is found 

 in nearly all vegetables. 



Silica, or the earth of flints, is met with in beautiful 

 transparent crystals, in the depths of the mine ; in all 

 rock and soils we find it. In the bark of many plants, 

 particularly the grasses, it is discovered, forming the 

 hard supporting cuticle of the stalk, in wheat, the Dutch 

 rush, the sugar-cane, the bamboo, and many other 

 plants. 



