COLLECTION OF LIGHT GASES. 



81 



therefrom will be collected in the jar, displacing the heavier air 

 the flask may be conveniently supported by a clamp, such as i 

 shown in fig. 44, fixed on 

 to a retort stand (fig. 6), 

 whilst the jar should be 

 held by the hand or 

 another clamp, so that the 

 tube passes up inside it 

 as far as possible. After 

 the liquid has been 

 warmed in the flask for 

 a minute or so, the strong 

 current of ammonia gas 

 passing upwards through 

 the tube will have pretty 

 thoroughly displaced all 

 the air in the jar, which 

 may then be corked up 

 with a well-greased cork 

 or stopper, and set on one 

 side for use when several 

 jars have been similarly 

 collected. Fig. 43. Flask and Fig. 44. Clamp. 



Expt. 76. To Show Delivery Tube 



the Solubility of Am- 

 monia Gas in Water or Alcohol. Prepare a jar or narrow closed 

 tube full of ammonia gas as just directed, and, without closing it 

 with a cork, carefully lift it off the delivery tube from which the 

 gas escapes, and quickly set it mouth downwards in a tumbler of 

 water ; the water will soon begin to dissolve the ammonia gas, the 

 effect of which is that the atmospheric pressure will force the water 

 up in the tube until it nearly fills it. If little or no residual air is 

 mixed with the ammonia gas in the tube, the water will rise almost 

 to the very top, leaving only a small bubble undissolved; but if much 

 air is mixed with the ammonia, the water will rise to a proportion- 

 ately less extent. This experiment illustrates the different degree 

 of facility with which water dissolves ammonia gas and ordinary 

 air, the former being readily dissolved, whilst the latter is 

 scarcely affected. Instead of water, alcohol (methylated spirit) 

 may be used with much the same results. 



Expt. 77. To make a Miniature Fountain. The easy solu- 

 bility of ammonia in water and the tendency of the atmospheric 

 pressure to force water into a partial vacuum caused by this solution 

 or absorption, causing a fountain to play, may be thus shown. 



