Fig. 108.
a. Gas jar containing nitrogen, n, standing on b, another jar full of oxygen, o. The taper, c, is extinguished at n, and relighted at o. d d. Stand supporting the jars.
Fourth Experiment.
It was the elegant, the accomplished, but ill-fated Lavoisier who discovered, by experimenting with quicksilver and air, the compound nature of the atmosphere; and it was the same chemist who gave the name of azote to nitrogen; it should, however, be borne in mind that it does not necessarily follow because a gas extinguishes flame that it is a poison. Nitrogen extinguishes flame, but we inhale enormous quantities of air without any ill effects from the nitrogen or azote that it contains; on the other hand, many gases that extinguish flame are specific poisons, such as carbonic acid, carbonic oxide, cyanogen, &c.
Lavoisier's experiment may be repeated by passing into a measured jar, graduated into five equal volumes, four measures of nitrogen and one measure of oxygen; a glass plate should then be slid over the mouth of the vessel, and it may be turned up and down gently for some little time to mix the two gases, and when the mixture is tested with a lighted taper, it is found neither to increase nor diminish the illuminating power and the taper burns as it would do in atmospheric air. (Fig. 109.)
Fig. 109.
a. Gas jar divided into five equal parts. b B. Section of pneumatic trough, to show the decantation of gas from one vessel to another. The gas is being passed from c to a, through the water.