52 AJIERICAN AGRICULTURE. 



atmospheric air on applying a lighted taper, the combustion 

 forming water. 



It is largely evolved from certain springs, in connexion 

 with carbon or sulphur, and 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 about the village of Fredonia, N. Y., 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 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 combination with chlorine, one of the ele- 

 ments of salt, it constitutes the muriatic, one of the strongest 

 of the acids. 



Ammonia. The most frequent condition besides wafer in 

 which hydrogen is mentioned in connexion with vegetation, 

 is when combined with nitrogen in the proportion of 3 of the 

 former in bulk, to 1 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 6-10ths the den- 

 sity of the atmosphere. By strong compression at a low 

 temperature, it may be condensed to a liquid having rather 

 more than 3-4ths the specific weight of water. It is never 

 found in a tangible shape, except in combination with acids, 

 forming carbonates, nitrates, sulphates, muriates, &c. of 

 ammonia. 



NITROGEN exists in the atmosphere to the extent of about 

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

 this connexion, is in diluting the oxygen, which in its pure 

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

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

 attraction of undiluted oxygen for iron, that a wire ignited 

 by a taper and plunged into a jar of oxygen gas, will itself 

 take fire and rapidly melt into irregular drops. This is 

 nothing more than an illustration of the principle exhibited 



