CHEMISTRY. 45 



which combustion does not. The latter gas is changed by the 

 electricity of the air to carbonic acid and water. 



The evolution of carbon from volcanoes, and fissures in the 

 earth in volcanic regions, is immense. In the ancient volcanic 

 region Eifel, on the bank of the Rhine, an annual evolution 

 takes place, according to Bischoff, of 27,000 tons of carbon. 

 Some carbon is absorbed by the waters of seas and oceans, 

 which is not, as far as we know, restored to the atmosphere. 

 Vegetable matters carried away by water, deposited and em- 

 bedded in beds of sand and clay, are thus prevented from 

 decaying, and their carbon is consequently lost. These are 

 two sources of loss of carbon: and although the balance 

 between its production and consumption is nearly equal, "still, 

 according to Prof. Johnston, there is supposed to be a slight, 

 permanent loss to the entire mass of our atmosphere. 



NITROGEN ITS PROPERTIES AND RELATIONS. 



Nitrogen is widely diffused through nature, constituting 

 nearly four-fifths of the atmosphere, and existing in many 

 vegetable, and most animal substances. It is destitute of 

 color, taste or odor, and is a little lighter than common atr ; it 

 is incapable of supporting combustion or animal life, but, like 

 hydrogen, it has no positively poisonous properties. Water 

 absorbs it in very small quantity: it is in fact distinguished for 

 negative properties, the reason why it does not sustain com- 

 bustion and animal life, appears to be merely the Absence of 

 oxygen. Its use in the atmosphere seems to be only to dilute 

 the oxygen sufficiently to render it fit for respiration. 



Nitrogen combines with oxygen and forms acids and oxides. 

 Its combining number is 14. Nitrogen may be obtained by 

 burning phosphorus under a bell glass over water. It does 

 not enter into the composition of any of the mineral con- 

 stituents of the earth's crust, except coal, which is of vegetable 

 origin. Nitrogen forms an important part in the growth of 

 both animals and plants. 



