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.