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CHEMISTRY. 



displaces the air in the jar, pushing it upward as water 

 would oil. In order that it may do this quietly and ef- 

 fectually, the jar is so placed that the end of the tube is 

 near the bottom. So, also, we can pour this heavy gas from 

 one vessel into another, the same displacement of air taking 

 place in this case. The comparative weights of air and this 

 gas may be shown by the experiment represented in Fig. 

 23. An empty beaker that is, a glass vessel full of air 

 is first balanced on a scale; then carbonic anhydride is 

 poured into it, of course causing the beaker to go down. 



Fig. 23. 



105. Liquefaction and Solidification of Carbonic Anhydride. 

 By an apparatus which subjects carbonic anhydride to 

 great pressure and cold this gas can be made fluid, and even 

 solid. As a solid it is a very peculiar substance, of a white 

 color, appearing much like dry snow. If held in the hand 

 it will destroy the skin like red-hot iron. The enormous 

 degree of pressure required to liquefy carbonic anhydride 

 is shown by the fact that the apparatus once exploded 

 in Paris, killing an assistant engaged in the experiment. 



