Marl. 95 branches; the one in which the argill exceeds, or at leaft amounts to 20 per ct. of the whole refiduum; the other, in which the liliceous in- gredient amounts to more than 80 per ct. of the whole refiduum. This diftindfion, which is of fotne importance in agriculture, cannot be di- redtly made but by means of a chemical analyfis ; however, it may be inferred from the property which the refiduum, after folution, has or has not of making a good brick; if it cannot be formed into a brick, then the filiceous ingredient ex ceeds; if it can be made into a brick, and this brick is liable to crack in drying, then the argil- laceous ingredient exceeds. ad Family. In a ftony or indurated ftate. Verhärteter Mer gel of Werner. Yellowifh white, or yellowifh or bluifh grey, or Ifabella yellow or brown, or reddifh or yellow- ilh brown, or brick red, or fleih coloured, or greyifii black. Surface often dufty. Luftre o. Tranfparency 0. Fradfure earthy, fometimes inclining to the fplintery, or conchoidal, frqqucntly flaty. Hardnels from 5 to 7. Spec. grav. (when it can be taken) front 2,3 to 2,7. It is fufible by a heat of 133” into a dark green compadt glafs. Mort Irequently crumbles loon after immer- fion in water. It effervcfccs ftrongly with acids, and by folu tion therein lofes from 0,25 to 0,32 of its weight. 6 The