304 HYDRO-CARBONS. 



chlorine performs in nature is a great and impor- 

 tant one. Combined in muriate of soda, we may 

 trace it in large quantities through the three kingdoms 

 of nature, and the universal employment of salt as a con- 

 diment indicates the importance to the animal economy 

 of the elements composing it. Iodine has been traced 

 through, the greater number of marine plants, existing, 

 apparently as an essential element of their constitution ; 

 in some land plants it has also been found, particularly 

 in the Armeria maritima, when this plant grows near 

 the sea :* it has been detected in some mineral springs, 

 and in small quantities in the mineral kingdom t com- 

 bined as iodide of silver, and in the aluminous slate 

 of Latoip in Sweden. J Bromine is found in sea- 

 water, although in extremely minute quantities, in a few 

 saline springs, and in combination with silver ; but we 

 have no evidence to show that its uses are important in 

 nature. 



Hydrogen, again, unites with carbon in various pro- 

 portions, producing the most dissimilar compounds. 

 The air evolved from stagnant water, and the fire-damp 

 of the coal mine, are both carburetted hydrogen ; and 

 the gas which we emply so advantageously for illumina- 

 tion, is the same, holding an additional quantity of 

 carbon in suspension. Naphtha, and a long list of 

 organic bodies, are composed of these two chemical 

 elements. 



These combinations lead us, naturally, to the con- 

 sideration of the great chemical phenomena of combus- 

 tion, which involve, indeed, the influences of all the 

 pnysical powers. By the application of heat, we pro- 



* Chemical Gazette, 1849. 



f Iodide of silver has been found at Albarradon, near Mazapil, 

 in Mexico. Iodide of mercury, of a fine lemon-yellow colour, has 

 been discovered in the sandstone of Casas, Viegas, Mexico, 

 Algers ; Phillips' Mineralogy. 



I GENTELE'S Eeports of the Stockholm Academy. 



