98 CHEMISTBY. 



at length will go out. It is prudent always to use this test 

 before going down into a well or a pit. It is to be remem- 

 bered that if the light merely burn dimly on coming near 

 the bottom, there is danger, as you will understand by re- 

 calling what is said in 107. There are various means re- 

 sorted to for ridding wells of this gas. One is to lower 

 into the well a pan of recently heated charcoal. This will 

 absorb into its pores 35 times its own bulk of this gas. An- 

 other is to burn a bundle of straw held to one side in the 

 well. The fire occasions an upward current in the gas, the 

 air going down on the other side to take its place. An- 

 other expedient is to bail out the gas with a bucket. This 

 can be done owing to its great specific gravity. The bucket 

 comes up to the mouth of the well apparently empty, but 

 actually full of the gas, as you might find by trying with a 

 lighted candle. 



124. Fumes of Burning Charcoal. If charcoal be burned 

 in a chafing-dish or open furnace in a close room, we have 

 the production of carbonic anhydride under circumstances 

 similar to those attending its production in a well. The air 

 in the room is comparatively still, and it is shut in. Life 

 has often been destroyed in this way. It is not carbonic 

 anhydride alone that does this, for, as stated in 112, there 

 is produced with this more or less of a still more deadly 

 poison carbonic oxide. The grand remedy, when we find 

 persons suffering from the fumes of burning charcoal, is to 

 open all the doors and windows, so that these gases may 

 be speedily diffused in the gases of the atmosphere, and the 

 reviving pure air from without be introduced into the lungs 

 of the sufferers. 



125. Carbonic Anhydride Discharged from the Lungs. 

 Every time that we breathe out we add to the carbonic an- 

 hydride in the atmosphere around us. That this gas is thus 

 discharged from the lungs can be proved by a very simple 



