something analogous to hygrometric action) more than another. But even when the mercury returned to its place in the gauge, there were anomalies which seemed to imply, that a substance, supposed to be one, might be a mixture of two or more. It is, of course, essential that the gauge be preserved at the same temperature through-out the observations.
Muriatic acid.—This substance did not freeze at the lowest temperature to which I could attain. Liquid muriatic acid dissolves bitumen; the solution, liberated from pressure, boils, giving off muriatic acid vapour, and the bitumen is left in a solid frothy state, and probably altered, in some degree, chemically. The acid unites with and softens the resinous cap cement, but leaves it when the pressure is diminished. The following are certain pressures and temperatures which, I believe, are not very far from truth; the marked numbers are from experiment.
| Fahr. ° |
Atmospheres. | Fahr. ° |
Atmospheres. | Fahr. ° |
Atmospheres. | |||
| √ | -100 | 1.80 | √ | -53 | 5.83 | √ | -5 | 13.88 |
| √ | -92 | 2.28 | -50 | 6.30 | √ | 0 | 15.04 | |
| -90 | 2.38 | √ | -42 | 7.40 | 10 | 17.74 | ||
| √ | -83 | 2.90 | -40 | 7.68 | 20 | 21.09 | ||
| -80 | 3.12 | √ | -33 | 8.53 | √ | 25 | 23.08 | |
| √ | -77 | 3.37 | -30 | 9.22 | 30 | 25.32 | ||
| -70 | 4.02 | √ | -22 | 10.66 | √ | 32 | 26.20 | |
| √ | -67 | 4.26 | -20 | 10.92 | 40 | 30.67 | ||
| -60 | 5.08 | -10 | 12.82 | |||||
The result formerly obtained[1] was forty atmospheres at the temperature of 50° Fahr.
Sulphurous acid.—When liquid, it dissolves bitumen. It becomes a crystalline, transparent, colourless, solid body, at -105° Fahr.; when partly frozen the crystals are well-formed. The solid sulphurous acid is heavier than the liquid, and sinks freely in it. The following is
- ↑ Philosophical Transactions, 1823, p. 198.
