Itura, for example, belonging to the former, has protrusible scent-emitting processes at the end of the abdomen; and Thyridia has scent-producing tufts of hair on the edge of the posterior-wing.
T intervals, varying from a few weeks or months to a few years, has broken out into eruption, sometimes emitting only steam, ist and scoriae, but frequently also streams of lava.
- The same spectrum may show differences according to the physical conditions under which the body emitting the spectrum is placed.
It fuses at 62.5°C. (Bunsen) and boils at 667°, emitting an intensely green vapour.
With the gas in excess a heavy lurid flame emitting dense volumes of smoke results, whilst if it be driven out in a sufficiently thin sheet, it burns with a flame of intense brilliancy and almost perfect whiteness, by the light of which colours can be judged as well as they can by daylight.