NON-COMBUSTIBLE GASES. 175 



LOCALITIES. 



This gas is given out in considerable abundance, and in a state of purity or nearly so, in 

 the town of Hoosick in Rensselaer county, at Lebanon in Columbia county, Canoga in Seneca 

 county, and at Chateaugay in Franklin county. These localities are particularly described 

 under the head of Nitrogen Springs (page 133). 



CARBONIC ACID. 



Carbonic Acid. Cleaveland and Shepard. — Gasibrmige Kohlen Saure. Mohs. — Acide Carbonique. Beudaut. 



Description. Gaseous, colourless, inodorous, and uninflammable ; soluble in water, to which 

 it communicates an agreeable subacid taste. Its specific gravity is 1521, compared with air 

 as 1000. It possesses acid properties both when free and when in solution. When test 

 paper is reddened by it, the original colour is restored upon the application of heat. It extin- 

 guishes all burning bodies, and when breathed in any quantity, is fatal to life. 



Composition. Carbon 27.4, oxygen 72.6. Its formula is COj. 



Uses. In the form of solution in water, carbonic acid is largely consumed as a beverage 

 under the name of soda water. It is also the basis of other effervescing drinks. The quan- 

 tity of. gas absorbed by water is much increased by pressure ; and when this pressure is 

 removed, the gas escapes with effervescence. 



In consequence of the great expansibility of the solidified gas, it was at one time supposed 

 that it would be a valuable moving power, but this idea is now abandoned. 



LOCALITIES. 



Carbonic acid is often found in the bottoms of wells, caverns, and other similar situations, 

 in considerable quantities. In such cases its occurrence is supposed to be owing to certain 

 decompositions of carbonate of lime which are effected below the crust of the earth, as the 

 acid, though ever so frequently removed, is again produced. Its presence may be detected 

 by introducing a lighted candle into the suspected air, when, if carbonic acid be present, the 

 candle will be extinguished. This is a precaution which should always be used before 

 descending into wells or unexplored caverns, especially in limestone countries. Many lives 

 have been lost, through want of attention to this simple test of the presence of this gas. 

 As its specific gravity is considerably greater than that of atmospheric air, it may be removed 

 from wells by large buckets or tubs in the same manner as water. Pure slaked lime may 

 also be used for the same purpose, as the carbonic acid readily combines with it and forms 

 carbonate of lime. 



Most of our wells and springs contain a small quantity of carbonic acid, and from many of 

 our mineral springs it is abundantly evolved. The most remarkable in this respect are the 

 springs of Saratoga and Ballston, where the quantity of this gas which is given out is some- 

 times so great as to resemble a volcanic eruption. I have been informed that some years 

 since there was a discharge of this gas from the creek in the village of Ballston, which threw 



