Having its ignition point below that of ordinary gas, it can be ignited by any redhot carbonaceous matter, such as the brightly glowing end of a cigar.
By weight of carbonaceous material.
Evidence from traces of organization is alone ' conclusive; the presence of carbonaceous matter, though a useful indication, may be deceptive, for the organic substance may have been derived from other sources than the body which left the impression.
More usually, however, the carbonaceous film is thin, and merely shows the impress of the medullary cast within; (3) petrified specimens of all parts - stem, roots, leaves and fructifications - showing the internal structure, more or less perfectly preserved.
Like these they require water, small but indispensable quantities of salts of potassium, magnesium, sulphur and phosphorus, and supplies of carbonaceous and nitrogenous materials in different stages of complexity in the different cases.
Usually the original organic substance remains as a thin carbonaceous layer forming the surface of the cast, but sometimes it has entirely disappeared.
The earlier supporters of the organic theory held that it was a product of the natural distillation of coal or carbonaceous matter; but though in a few instances volcanic intrusions appear to have converted coal or allied substances into oil, it seems that terrestrial vegetation does not generally give rise to petroleum.
The great majority of specimens of fossil fern-like plants are preserved in the form of carbonaceous impressions of fronds, often of remarkable perfection and beauty.
The larger materials include gravel of all degrees of coarseness; carbonaceous matter is often an important element.
The fat (which when separated we know as butter) and the lactose constitute the carbonaceous portion of the milk regarded as food.