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New Zealand Herald, Volume XXVIII, Issue 8631, 29 July 1891, Page 5

i . . _— , . ..',..;.. ; Th« following particulars about a sub stance that has been named " slag wool'' may be read with interest:—" Slag wool" is a waste substance which issues from ironmelting furnaces. It is formed by the separation of the earthy matter from the ore, and looks like coarse, dark glass if allowed to cool as it comes from the furnace. : Formerly it was thrown away as valueless, but since a process of converting it into" wool" has been discovered, it is utilised for many purposes. This mineral wool is formed by causing a jet of steam to play upon the stream of molten slag as it issues from the furnace. This has the effect of breaking up the melted mass into countless small, beadlike particles, so light that they fly in every direction. Each of these tiny beads carries ' behind it a delicate thread of finely-spun slag, so that one is reminded of a comet with its tail. To collect these threads, and to separate the fibres from the beads or ; heavier portions of the slag, the steam jet is arranged at the mouth of an open cylinder of sheet iron, in which a strong air current is induced by means of additional jets of steam. The tube or shaft is furnished with a shield or striking plate which detains the heavier particles, while the lighter slag wool is carried by the draught into a large chamber resembling a gigantic meat-safe, its walls being formed of wire netting with about 16 meshes to the square inch. Here the steam condenses and escapes, leaving the slag wool, which now has the appearance of snowflakes, deposited on the floor of the chamber or clinging co its wire walls. The filaments or flakes are then broken up and felted together, when they look and fcor like wool. This mineral wool is extremely light and absolutely fireproof— properties which make it useful for a largo variety of purposes. It is a marvellous non-conductor of heat and sound, which renders it valuable for packing between the floors of rooms and in the spaces between partitions. It serves as an excellent covering for boilers, heating- :.., pipes, and such things. It can bo woven into cloth, and as such makes tire-prool _-... curtains for theatres, and it might not be a bad plan to make clothes out of it for children who persist in playing near the fire. . lb is so porous that it will absorb and retain large quantities of water like a sponge, and it is also an antiseptic, that is, a substance which resists or corrects putrefaction. JO » is useful, therefore, as a dressing for wounds ■ . as well as for other medical purposes.