624 



HISTORY OF SCIENCE. 



In prosecuting these experiments Faraday in 1825 condensed small 

 quantities of certain vapours from gas prepared by the distillation of 

 oil. These proved on examination to be compounds of hydrogen and 

 carbon, and among them was one which long afterwards became of 

 much scientific interest, and the starting-point of large chemical indus- 

 tries. This was benzine or benzol, the parent of all the now well-known 

 aniline colours, to which reference will again be made in the sequel. 



Here we may refer to the experiments of DR. ANDREWS of Belfast 

 (1862), who was the first to demonstrate the continuity of the liquid 



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FIG. 314. HOFMANN. 



and solid states. When carbonic acid gas was liquefied in a tube by 

 pressure, and the tube was gradually raised to the temperature of 88 R, 

 the demarcation between the liquid below and gas above became 

 fainter, and at length disappeared, the whole space being then filled 

 with a uniform fluid, which on a slight diminution of either tempera- 

 ture or pressure exhibited a peculiar appearance of flickering stria. 

 At the temperature of 88 R carbonic acid was therefore capable of 



