58 AMERICAN AGRICULTURE. 



It is larg sly evolved from certain springs, in connection 

 with carbon or sulphur. This is called carburetted and sul 

 phuretted hydrogen, an offensively pungent and inflamma- 

 ble gas. So abundantly is this emitted from the earth in 

 some places, that it is used for economical purposes. The 

 inhabitants in the village of Fredonia, New York, light their 

 buildings with it; and some of the salt manufacturers in 

 the valley of the Ohio, apply it to evaporating the water of 

 the saline springs. Carburetted hydrogen is the gas now 

 employed for lighting cities. It is manufactured from oils, 

 fat, tar, rosin and bituminous coal, all of which yield large 

 quantities of carbon and hydrogen. Both the carbon and 

 hydrogen are entirely consumed with a brilliant light, when 

 inflamed and exposed to the oxygen of the atmosphere. It 

 is the residuum of the volatile portion of these substances, 

 after driving off the gas, which makes the ammoniacal 

 liquor so useful as a manure ; all the nitrogen, with a part 

 of the hydrogen, remaining in the liquid. In combination 

 with chlorine, one of the elements of salt, it constitutes the 

 muriatic, one of the strongest of the acids. 



Ammonia. The most frequent condition in which hy- 

 drogen is mentioned, in connection with vegetation, besides 

 water, is when combined with nitrogen, in the proportion of 

 three of the former in bulk, to one of the latter ; and by 

 weight, 17.47 of the first, to 82.53 of the last, in every 100 

 parts, composing the volatile alkali, ammonia, which is 

 about T 6 ff the density of the atmosphere. By strong com- 

 pression at a low temperature, it may be. condensed to a 

 liquid, having rather more than the specific weight of 

 water. It is never found in a tangible shape, except in 

 combination with acids, formimg carbonates, nitrates, sul- 

 phates, and muriates of ammonia. 



Nitrogen exists in the atmosphere to the extent of about 

 79 per cent. The principal purpose it appears to fulfil in 

 this connection; is in diluting the oxygen, which in its pure 

 state, acts with too great intensity on animal life, in com- 

 bustion, and all its varying combinations. So great is the 

 attraction of undiluted oxygen for iron, that a wire, plunged 

 into a jar of oxygen gas and ignited by a taper, will readily 

 take fire and melt into irregular drops. This is nothing 

 more than an illustration of the principle, exhibited in an 

 intense degree, in the gradual rusting which takes place in 

 the air at its ordinary temperature ; or the more rapid for- 

 mation of the scales under the heat of the blacksmith's forge. 



