CARBONIC ACID. 



369 



(c.) Mix smoke with this gas, by extinguishing in it a burning chip 

 or paper, or by burning a cork with a red hot iron borer, at the ves- 

 sel's mouth, or better by exploding gun powder in a pendent spoon, 

 in ajar, or globe filled with carbonic acid ; see the figure on p. 368. 



(d.) The gas is thus rendered visible, and exhibits distinct fluc- 

 tuations and currents. 



(e.) Butterflies and other insects of delicate colors are killed in this 

 gas, and better than by sulphurous acid gas.* 



(f.) By a cylindrical jar, containing carbonic acid gas and a little 

 water, with the aid of a pendent candle, we may show the phenome- 

 na of the damp in wells and caverns. In the annexed apparatus, two 

 ounces of the carbonate of am- 

 monia, and half as much deep 

 orange colored nitrous acid, being 

 placed in the three necked bottle, 

 will evolve carbonic acid gas, 

 which will thus be rendered visi- 

 ble in its ascent, and in its over- 

 flow beneath the cover of the up- 

 per vessel. This being removed 

 and a candle introduced, it will 

 be extinguished. The gas can 

 be drawn off at A ; its current 

 will be visible, and it will extin- 

 guish a burning taper held in its 

 course ; or it can be drawn like 

 a liquid into any other vessel con- 

 taining a lighted candle which it 

 will thus put out. If either ori- 

 fice of the bottle be opened, all 

 the gas in the upper vessel will 

 flow out. Dr. Hare. A long 

 necked funnel may be substituted 

 for the upper vessel. 



(g.) Sp. gr. 1.527 ; 100 cub. inch, weigh at 60 Fahr. and 30 in. 

 Bar. 46.59, whereas air weighs 30.50.f 



(h.) We may pour the contents of one jar into another, and exa- 

 mine by a pendent candle how high the gases rise. 



(i.) We may collect it by a bent tube passing into a bottle filled 

 only with common air, which it will expel. 



* Entomologists prefer to kill them simply by means of heat, immersing them in 

 boiling water, in close vessels. 



t It is said that Dr. Prout has recently ascertained that it is as high at least as 31 

 grs. Addenda to Turner, 2d edition. 



47 



