In the same way some of the more fixed essential oils may be used, as dry oil of turpentine; and even a portion of the condensed liquor itself as that part which requires a temperature of 220° or 230° for its ebullition; care being taken to estimate the expansion of the gas by the vapour of the liquid, which may readily be done by a known portion of common air preserved over the liquid as a standard.
With reference to the proportions of the different substances in the liquid as obtained by condensation of oil-gas, it is extremely difficult to obtain anything like precise results, in 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 evaporation in a flask, for every 10° in elevation of temperature, the substance being retained in a state of ebullition.
| 100 parts at | 58° | parts | differenes. | ||
| had lost at | 70 | . . . | 1.1 | ||
| 1.9 | |||||
| 80 | . . . | 3.0 | |||
| 2.2 | |||||
| 90 | . . . | 5.2 | |||
| 2.5 | |||||
| 100 | . . . | 7.7 | |||
| 2.4 | |||||
| 110 | . . . | 10.1 | |||
| 3.1 | |||||
| 120 | . . . | 13.2 | |||
| 2.9 | |||||
| 130 | . . . | 16.1 | |||
| 3.2 | |||||
| 140 | . . . | 19.3 | |||
| 3.1 | |||||
| 150 | . . . | 22.4 | |||
| 3.2 | |||||
| 160 | . . . | 25.6 | |||
| 3.4 | |||||
| 170 | . . . | 29.0 | |||
| 15.7 | |||||
| 180 | . . . | 447. 4 | |||
| 23.4 | |||||
| 190 | . . . | 68.1 | |||
| 16.1 | |||||
| 200 | . . . | 84.2 | |||
| 7.4 | |||||
| 210 | . . . | 91.6 | |||
| 3.7 | |||||
| 220 | . . . | 95.3 | |||
| 1.3 | |||||
| 230 | . . . | 96.6 | |||
The residue, 3.4 parts, was dissipated before 250° with slight decomposition. The third column expresses the quantity volatilized between each 10°, and indicates the existence of what has been described as bicarburet of hydrogen in considerable quantity.
