172 CHEMISTRY. 



Light and Motion. 



It is known by experiment, that every sudden 

 stroke, every rapid motion, impressed on a mass of 

 air which Cannot yield with sufficient quickness, ex- 

 cites in it a degree of light. 



Gas. 



This term is applied to all permanently elastic 

 fluids of an aerial form, except common atmospheric 

 air. 



Weight of the Gases, fyc. 



100 cubic inches of oxygen, weigh . 33*75 grains. 



Ditto ditto chlorine . . . 75-375 



Ditto ditto iodine (vapour of) 264-937 



Ditto ditto hydrogen ... 2-25 



Ditto ditto steam .... 18'80 



Ditto ditto nitrogen or azote 29*25 



Ditto ditto common air . . 30*20 



Ditto ditto carbonic acid . . 46*575 



Ditto ditto carburetted hydrogen 30*15 



Ditto ditto cyanogen . . . 54*9 



Liquefaction of Gases by High Pressure. 



Mr. Faraday, by high pressure, produced quanti- 

 ties of liquid carbonic acid. In this experiment 

 glass tubes 8 inches long, and -j-^ths of an inch in- 

 ternal diameter, had a pressure on their internal sur- 

 face of 8000 pounds weight, without injuring or 

 breaking the glass. 



Mr. Perkins's most remarkable result is, the lique- 

 faction of atmosphere under a pressure of 1200 at- 

 mospheres. 



It is probable that, in the course of time, the 

 liquids resulting from the condensation of the gases 

 will be applied as mechanical agents. 





