22 LESSONS ON CHEMISTRY. 



tilled water, that is, water from which the air has been ex- 

 pelled by boiling, like the fire, it would soon die, — we must 

 " give it air," or it will not flom-ish. (c) If we take a piece 

 of wax taper, and fix it on a cork so as to allow it to float 

 on a basin of water, and then light it and invert over it a 

 large, wide-mouthed bottle, the taper will continue to bum 

 for a short time, but will at last die out; and if we now 

 cautiously introduce a second lighted taper into the bottle, 

 it will be immediately extinguished, (d) If, instead of a 

 lighted candle or a plant, we were to place in a closed bottle 

 a mouse, or any small animal, it would live for only a short 

 time, and the life of a second animal, introduced after the 

 death of the first, would, like the light of the candle, be im- 

 mediately extinguished. Air, therefore, undergoes a change 

 by supporting the life of plants and animals, or the flame of 

 a candle. It appears to contain something indispensable to= 

 both animal and vegetable life, and deprived of which it is 

 incapable of feeding flame or supporting animal existence. 



7. The air is thus proved to contain a substance remark- 

 able for its influence in supporting life and flame. This sub- 

 stance seems to form but a small portion of its bulk and to 

 be soon consumed. Such indeed we know from chemical 

 investigation is the case, this substance being a gas, one af 

 the simple bodies termed Oxtgen, which forms only about a 

 fifth part of the atmosphere. This gas, besides forming a part 

 of the air, is also locked up in immense quantities in combi- 

 nation with rocks and minerals, and by exposing some of 

 these to heat, we can decompose them, in the same manner 

 that the limestone is decomposed in the kiln, and drive off 

 their oxygen so that we can procure it in a separate form,* 



* As it is most desirable that ..the teacher should" prepare small 

 quantities of the gases described in the lessons, and illustrate their pro- 

 perties to his pupils, it will be useful to describe the apparatus and ope- 

 rations required for their preparation and collection. When a bottle 

 is filled with water, as already described, it may be raised up in 

 the water, and will remain full, provided its mouth be kept immersed. 

 If we now plunge another bottle, in common language termed empty, 

 but really containing air, into the water in such a manner as to allow 

 the bubbles which escape to rise imder the mouth of the bottle filled 

 with water, the air will gradually drive out the water, and occupy its 

 place. If we bring a bottle full of gas, or a tube from which it is es- 

 caping, under the mouth of a bottle of water as just described, the 

 water will in like manner be driven out, and we will procure a bottle 

 of the gas, which we may remove from the basin and preserve foi- 



