OF AGRICULTURE, 227 



burning candle for a short time ; then agitate in the 

 jar a little lime water. It will become turbid at once. 

 With a glass tube, or a tobacco-pipe, breathe through 

 a portion of clear lime-water, and the same effect 

 will be produced. 



Carbonic acid exists in all natural waters, and 

 form many mineral springs, as those at Saratoga ; 

 it constantly escapes, causing the water to sparkle, 

 and giving it a pungent, lively taste. Soda-water is 

 such as has been charged artificially with carbonic acid. 



Its Physiological Effects. Carbonic acid gas, when 

 respired, destroys animal life. This it does in two 

 ways: \vhen breathed pure it produces spasms of the 

 glotis, closes the air passages, and thus kills suddenly 

 by suffocation. When diluted with ev"en ten times its 

 bulk of air, and taken into the system, it acts as a 

 narcotic poison, gradually producing stupor, insensi- 

 bility and death. 



Persons sleeping in close apartments are sometimes 

 suffocated by the fumes ef burning charcoal carbonic 

 oxyde as already stated above, but so many persons 

 are killed by going into w^ells that I state it again. It 

 often accumulates at the bottom of wells and in 

 cellars, stifling those who may unwarily descend. To 

 test its presence in such cases, lower a lighted candle 

 into the suspected places. If it is not extinguished, 

 the air may be breathed for a short time ; if the light 

 goes out, it will be necessary before descending, to 

 throw down some dry, slacked lime or raise and 

 depress an umbrella in it repeatedly, in order to 

 mingle it with the air. 



4 To resuscitate those who have been exposed to the 

 poisonous action of carbonic acid, dash cold water 



