NITROGEN. 



SEC. II. NITROGEN OR AZOTE. THE ATMOSPHERE. 



NITROGEN. 



1. Name. As it is the basis of nitric acid, it is now called nitro- 

 gen ; its former name was from a, a Greek privative, and w?j, 

 life, signifying that which destroys life ; but the name is not distinc- 

 tive, many other gases being azotic. 



2. Discovery by Dr. Rutherford, at Edinburgh, 1772 ; Lavoi- 

 sier first separated it from the atmosphere, in 1775, and Scheele, 

 about the same time. 



3. Mode of obtaining. 



(a.) Burn phosphorus in a floating saucer or other earthen dish 

 under a bell glass over water ; the acid fumes are absorbed in half 

 an hour by the water, and sooner, if agitated with it ; and nitrogen 

 gas slightly phosphorized, remains. 



Solution of caustic potash, agitated with the gas in a bottle, quickly 

 separates both the phosphoric acid, and a little carbonic acid which 

 is sometimes mingled with it. 



(b.) With a gentle heat, dilute nitric acid, sp. gr. 1.20, acting on 

 lean muscle in a glass retort, evolves nitrogen. 



(c.) Iron filings and sulphur being mixed and moistened, and placed 

 in a saucer under a bell glass ; the oxygen is absorbed in three or 

 four days, and nitrogen remains. Other methods will be mentioned 

 farther on. 



4. PHYSICAL AND CHEMICAL PROPERTIES. 



(a.) Transparent, colorless, inodorous, tasteless, not sensibly ab- 

 sorbed by water. 



(b.) Sp. gr. .9722, air being 1. (Thomson.) 100 cub. in. weigh 

 29,652 grains. 



(c.) Its refractive power is very feeble. 



(d.) Combines with oxygen, and forms several very important 

 compounds nitric acid, the nitrous acids, nitric oxide gas, and ni- 

 trous oxide gas. 



(e.) No combination results from a mere mixture of the oxygen 

 and nitrogen ; owing to the repelling power of caloric, they would 

 probably remain forever in mixture, without change ; but they will 

 unite, if in the nascent state, or, if one of them is in that condition. 



(f.\ Combined with oxygen by electricity, nitrogen forms nitric acid.. 



(jr.) Still it is not a combustible in the common sense of that word ? 

 it does not fire by the approach of a candle to the mouth of a vessel 

 containing it, nor if previously mixed with oxygen gas. 



(h.) It is fatal to combustion. A burning match, candle, phos- 

 phorus, or any burning body is extinguished by immersion in this 



25 



