182 Mr. Faraday on fie'w Compounds 



home, put into a flask and distilled, its temperature being 

 raised by the hand. The vapour which came off", and which 

 caused the appearance of boiling, was passed through a glass 

 tube at 0°, and then conducted to the mercurial trough ; but 

 little uncondensed vapour came over, not more than thrice the 

 bulk of the liquid ; a portion of fluid collected in the cold 

 tube, which boiled and evaporated when the temperature was 

 allowed to rise ; and the great bulk of the liquid which re- 

 mained might now be raised to a comparatively high point, 

 before it entered into ebullition. 



A thermometer being introduced into another portion of 

 the fluid, heat was applied, so as to keep the temperature 

 just at the boiling point. When the vessel containing it was 

 opened, it began to boil at 60° F. As the more volatile por- 

 tions were dissipated, the temperature rose : before a tenth 

 part had been thrown off", the temperature was above 100°. 

 The heat continued gradually to rise, and before the substance 

 was all volatilized it had attained 250°. 



With the hope of separating some distinct substances from 

 this evident mixture, a quantity of it was distilled, and the 

 vapours condensed at a temperature of 0° into separate por- 

 tions, the receiver being changed with each rise of 10° in the 

 retort, and the liquid retained in a state of incipient ebullition. 

 In this way a succession of products were obtained, but they 

 were by no means constant; for the portions, for instance, 

 which came over when the fluid was boiling from 160° to 

 170°,' when re-distilled began to boil at 130°, and a part I'e- 

 mained which did not rise under 200°. By repeatedly recti- 

 fying all these portions, and adding similar products together, 

 I was able to diminish these differences of temperature, and 

 at last bring them more nearly to resemble a series of sub- 

 stances of different volatility. During these operations I had 

 occasion to remark, that the boiling point was more constant 

 at, or between 176° and 190°, than at any other temperature, 

 lai'ge quantities of fluid distilling over without any change in 

 the degree ; whilst in other parts of the series it was constantly 

 rising. This induced me to search in the products obtained 

 between these points for some definite substance; and I ulti- 

 mately succeeded in separating a new compound of carbon 

 and hydrogen, which I may by anticipation distinguish as bi- 

 carburet of hydrogen. 



Bi-carburet of Hydrogen. 



This substance was obtained in the first instance in the fol- 

 lowing manner. Tubes containing portions of the above recti- 

 fied products were introduced into a freezing mixture at 0° ; 



many 



