FLAX AND TOW.

99

The ferric-cyanide of potassium has been introduced into dyeing and calico-printing.In case an excess of chlorine has been used in preparing the above salt, Posselt rec-ommends to add to its solution, when near the crystallizing point, a few drops of potashe y, in order to decompose a green substance that is present, which takes place with thePrecipitation of a little peroxide of iron.

FIREARMS. Barrel-welding by Machinery .—The barrels of musquets, birding-Kuns, &c., or what are called plain, to distinguish them from those denominated stub orlisted barrels, have of late years been formed by means of rolls, a process in whichl he welding is first effected on a short slab of thick iron, and then the barrel is brought< *°'vn to its destined length, and form, by repeatedly passing it between a pair of rolls,9nat have been previously grooved to the exact shape of the barrel intended to be made.

This method has entirely superseded the skelp-welding by hand described in. theHie. of Man., p. 471, and is conducted as followsThe iron being thoroughly refined, and reduced into flat bars by the process de-scribed at length at p. 705, is cut by the shears into slabs or lengths of 10 to 12 inches,?-hd 10 to 10j lbs. weight, or less, according to the description of gun-barrel that is'"tended to be made. These slabs are then heated, and bent in their whole length, byPtcans of conveniently grooved bending rolls, until they assume the form of rough tubes,49 of the kind of section shown by A, Jig. 49. They are then placed on thehearth of the > reverberatory furnace {Did. p. 701), and brought to a fullwelding heat,"and as soon as the edges of a tube come to a semi-fluid state,I A it is taken out and passed between rolls having grooves somewhat smallerin diameter than the exterior of the tube, by which means the tubeis perfectly welded from end to end; and if care be taken in themanagement of the heat, and the juncture be kept clear of dirt and cinders, the iron' Vl, l be found perfectly homogeneous in every part, and there will be no appearancejmiatever of the seam where the edges came together. These tubes are repeatedly"Cated, and passed between the barrel rolls, which are of sufficient diameter to admit°f gradually decreasing grooves, the whole length of the intended barrel being indented°h their surfaces.

To preserve the tubular form, and insure regularity in the size of the bore duringl hc welding process, they are taken out of the furnace, bv thrusting into them a toolcalled a mandril b, which consists of a long rod of iron, having a short steel treblett onend, of the diameter that the bore of the barrel is meant to bore. This rod is soadjusted by means of a strong iron plate c, near its handle, which is of wood, and long,nat when passed with the heated tube on it between two tranverse holding bars, thea°rt steel treblett d, shall be found exactly between the point of impact of the barrel-r °Us, e e.

, adhesion of the hot iron to the surface of the rolls is strong enough to draw thet}> t * le mandril, which thus keeps the bore open from end to end, and by repeating. e process through the whole series of grooves in the rolls, the barrel is graduallyj. ° n gated, and brought down to the exact form required: any superfluous length at theis then cut olf. The breach end is then adjusted by the hammer—a tripple-seatelded on by hand if it be intended for a percussion lock, and then the barrel is readySo forward to the mill to be bored, turned, and finished,th ^^arrels formed. by this mechanical method are found to stand proof better thanth° Se . Wor ' £e( I by hand, because the heat is more equalized; and any imperfections in^original mass of iron are more dispersed over the whole extent of the tube.

Piet Wells lugram, of Bradford street, Birmingham , has lately perfected a very corn-fast for turning the exterior of gun-barrels of all descriptions, a process which is

a^uperseding the use of the grindstone, for equalizing the barrels of all kinds of fire-

55 * indebted for this article to Mr. Lovell, Director of the Royal Jrms Manufactory.

c nlosquET.

i ooq AX and TOW, or Codilla of Hemp and Flax , imported for home consumption in> 1,216,811 cwt.; in 1840, 1,256,322; Id. per ewt.