1826.] of Carbon and Hydrogen, 8fc. lOS 



consequence of the immense number of rectifications required 

 to separate the more volatile from the less volatile portions ; but 

 the following table will furnish an approximation. It contains 

 the loss of 100 parts by weight of the original fluid by evapora- 

 tion in a flask for every 10° in elevation of temperature, the sub- 

 stance being retained in a state of ebullition. 



100 parts at 58° parts differ. 



had lost at 70 M ... 



80 3-0 .... 



90 5-2 ..., 



100 7-7 ..., 



110 10-1 ... 



120 13-2 ... 



130 16-1 ... 



140 19-3 ... 



150 22-4 . . . 



160 25-6 ... 



170 29-0 ... 



180 44-7 ... 



190 68-1 .., 



200 84-2 . . . 



210 91-6 ... 



220 95-3 . . . 



230 96-6 ..., 



1-9 

 2-2 

 2-5 

 2-4 

 3-1 

 2-9 

 3-2 

 3-1 

 3-2 

 3-4 

 15-7 

 23-4 

 16-1 

 7-4 

 3-7 

 1-3 



The residue 3*4 parts was dissipated before 250° with slight 

 decomposition. The third column expresses the quantity vola- 

 tilized between each 10°, and indicates the existence of what 

 has been described as bi-carburet of hydrogen in considerable 

 quantity. 



The importance of these vapours in oil gas, as contributing to 

 its very high illuminating powers, will be appreciated, when it 

 is considered that with many of them, and those of the denser 

 kind, it is quite saturated. On distilling a portion of hquid, 

 which had condensed in the pipes leading to an oil gas gaso- 

 meter, and given to me by Mr. Hennel, of the Apothecaries' 

 Hall, I found it to contain portions of the bi-carburet of hydro- 

 gen. It was detected by submitting the small quantity of liquid 

 which distilled over before 190° to a cold of 0°, when the sub- 

 stance crystallized from the solution. It is evident, therefore, 

 that the gas from which it was deposited must have been satu- 

 rated with it. On distilling a portion of recent coal gas tar, as 

 was expected, none could be detected in it, but the action of 

 sulphuric acid is sufficient to show the existence of some of these 

 bodies in the coal gas itself. 



With respect to the probable uses of the fluid from compressed 

 oil gas, it is evident in the first place, that being thus volatile, it 



will, if introduced into gas which burns with a pale flame, give 



