[ 88 j 



is found to come out of ponds, burying-grounds, 

 and other places containing animal and vegetable 

 matter in a ftate of decay. Found alfo in the 

 earth where inflammable minerals are contained; 

 when, combining with atmofpheric air, it fome- 

 times fuddenly takes fire to the danger of the 

 miners, and by them called fire-damps. It is 

 obtained from moll kind of bodies; but the 

 greateft quantity may be extracted from zinc, by 

 means of diluted vitriolic acid; and from red-hot 

 iron, by pairing the (team of boiling water over 

 its furface. In like manner charcoal yields in- 

 flammable gas, called hydrocarbonate, combined 

 with the carbonic acid gas. It is this aeriform 

 fluid which floats frequently on marines, and 

 being fet on fire by electricity, or other means, 

 gives rife to the ignis fatuus. Hydrogen gas has 

 the property of diffolving and fufpending a variety 

 of fubftances, as iron, charcoal, fulphur, phof- 

 phorus, Sec, hence we have the names of phof- 

 phoric hydrogen gas, or phofphuret of hydrogen; 

 iulphuric hydrogen gas, or fulphuret of hydro- 

 gem ; with phofphorus it is called phofphorated 

 hydrogen gas, giving out a fcetid fmell, is impro- 

 per for refpiration, and takes fire fpontaneoufly in 

 coming in contact with the air, accompanied with 

 an explofion; and probably to the di (engagement 

 of gas, the ignis fatuus, playing about burying- 

 grounds and places where animals are putrifying, 

 may be attributed. 



Nitrous acid gas is difengaged from nitric 

 acid by various combuftible bodies, efpecially 

 metals, oils, mucillages, and alcohol. By the 

 action of the nitric acid on thefe fubftances it be- 

 comes 



