1825.] On neiv Compounds of Carbon and Hydrogen, $c. 157 



tionsj 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 remained 

 which did not rise under 200. By repeatedly rectifying 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 substances 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, large 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 ultimately succeeded 

 in separating a new compound of carbon and hydrogen, which 

 I may by anticipation distinguish as bicarburet of hydrogen. 



Bicarburet of Hydrogen. This substance was obtained in 

 the first instance in the following manner : Tubes containing 

 portions of the above rectified products were introduced into a 

 freezing mixture at ; many of them became turbid, probably 

 from the presence of water; one received at 176 (by which is 

 meant that that was the boiling-point of the contents of the 

 retort when it came over) became partly solid, crystals forming 

 round the side, and a fluid remaining in the centre ; whilst two 

 other portions, one received at 186 and the other at 190, 

 became quite hard. A cold glass rod being introduced into 

 one of these tubes, the mass within was found to resist con- 

 siderable pressure ; but by breaking it down, a solid part was 

 thrust to the bottom of the tube, whilst a fluid remained above: 

 the fluid was poured off, and in this way the solid portion partly 

 purified. The contents of the tube were then allowed to fuse, 

 were introduced into a larger and stronger tube, furnished 

 with another which entered loosely within it, both being closed 

 of course at the lower end ; then again lowering the tempera- 

 ture of the whole to 0, bibulous paper was introduced, and 

 pressed on to the surface of the solid substance in the large 

 tube by the end of the smaller one. In this wav much fluid 



