SCIENTIFIC NOTES.

Auckland Star, Volume XXI, Issue 4193, 24 November 1883, Page 10 (Supplement)

SCIENTIFIC NOTES.

A description is given in "Engineering " os the new copper zinc alloy, just introduced in London,and which it is claimed

possesses properties as superior to brass as those of bronze are to gun metal. The specific advantages presented by this new metal are chiefly great strength and toughness, and capacity for being rolled, forged, and drawn. It can bo made as hard as mild steel, and when melted is very liquid, producing sound castings of close fine grain, and the colour can bo varied from that of yollow brass to rich gun metal, the surface taking a fine polish, and, when exposed to tho air, tarnishing less than brass. When cast in sand, the metal has a breaking strain of twenty-ono to twenty-two tons per square inch ; when rolled or forged hot into rods, the breaking strain is found to be forty-three tons tho square inch.

Tho fact is now recognised by all architects that the stability of a building undor the influence of lire depends largely upon keeping the floors from giving way — a matter easily attained when they aro of iron |and pugging, but requiring special precautions when they are made of combustible materials. A practice is now being resorted to, to a considerable extent, by French builders, of protecting floors by placing upon them a half-inch layer of usphalt over an inch of argillaceous earth, both at top and bottom. A layor of plaster of Paris, fine concrete, cement, or clay, three or four millimetres (0.11 to o.ls)thick, or a paying of tiles, permits of waiting for assistance, by preventing the air from coming in contact with the wood and thus maintaining combustion. The industrial uses of slag seem to continually multiply. The nlaig; wool, as it is termed—produced by the impact of a steam jet with a stream of molten slag—is employed for covering steam boilers, steam pipes, ice houses, and cisterns, also as a protection against fire, a filter for chemicals, &c. ; paving blocks and building bricks are made by pulverising tho solid slag and then pressing the bricks in a preps; and glass is another product—the molten slag being taken in a ladlo from the blast furnace and poured into a Siemens furnace, where soda and silica aro added to the mass, according to the quality of tho slag used. Tho ingenuity of Horr Victor has enabled him to determine that the colour of water, when n erfectly pure, ib a shade between blue and green. Taking two glass tubes, forty millimetres in diameter and about 1.5 meters in length, he connected them by means of rubber tubing, forming a tube about seven'and ono-half meters long, both ends of this tube being fixed in glass plates and fitted with m«tal sockets, provided with brass nozzles for filling the tube. The tube was now placed in a perfectly horizontal position, and covered with a black cloth; upon looking through the empty, tube the field of vision appears colourleM.as the cloth and the metal sockets prevent the glass from exorting any influence; as soon, however, as the tube is filled with distilled water, an intense bluish green colour is observed. The process pursued in manufacturing fabrics composed of wool and cotten or other vegetable fibre, viz., to either card both materials separately, in order to subsequently mix them. up and spin the two into yarn known as merino or angola, or to mix ujp the animal and vegetable fibres before tarding, has the disadvantage of showing a quantity of small knots or irregularities on the surface of tho fabrics, thus deteriorating tho quality and value of the yarn. This difficulty, it is now found, may bo avoided by carding separately tho cotton, wool, or other fibre in a carding engine best suited to the particular substance treated ; theso cotton and wool cardings being then laid one on tho other, and subsequently passed through another carding engine, which thoroughly combines the different fibres together, when thoy are spun into yarn in the usual manner. The carding engine in this caso is sot, in Older to prevent the fibres entering tho card teeth further than is nocessary to insuro their parallel position. Prepared in this manner, the yarns are quite free of knots. One of tho astronomers at the Greenwich (Eng.) Observatory claims to havo measured thoheatfrom those well-known stars—Arcturus, tho leading brilliant of tho Herdsman, and Vega, tho chief star of the Lyre. From a careful measurement of their light tho equal splendour of these stars was long ascertained; but Arcturus shines with a ruddy, yellow light, while Vega exhibits a colour which has been compared to tho gleam of highly polished steel. Tho estimates of their heat correspond wieh the aspect of theso orbs, Arcturus emitting about twice as much as Vega. Minute, however, ib the heat received from either ; indeed, these measurements show that the heat roceivod from Arcturus is, sensibly, tho same as that from the face of a threeinch iron cube full of boiling water at a distance of 353 yards.

Tho town of Borcetto, France, claims to produce tho best quality of needles now supplied to tho mamkets of Europe, the processes of manufacture being in s<smo respects peculiar to this locality. The conversion of the steel wire into rough needles involves some twenty operations. The pointing is found to bo best accomplished by means of grindstones; by tho aid of a copper finger-stall, the workman holds fifty wires at a time, which are boated to redness by tho friction. After the sharpening, the operation cuts the wire into two, flattens the head, and anneals and punches the eyes. Tho tempering and annealing compriso nine operations. One million needles are polished at one time— live operations, each being repeated seven or eight times; the needles are put in hollow rollers with small hard stones and colza oil, the stones are gradually pulverised, and the friction of the powder gives the principal polish, oil and course Man being employed for thejfinal polish. Violent Changes in Brooks'?! Comet, Boston, Sept. 2-t.—The violent changes which are going on in the physical appearance of Brooks's comet, as noted in the despatch of Saturday night, still continue, as shown by tho observations mado at Harvard College Observatory last night

by Mr Chandler. The increase of light still continues, but at a less rapid rate, while instead of the sharp, small disc into which most of the light was collected, the nucleus isspreading out into aconfused, circular, nebulous patch of light, half a minute of an arc in diameter. The comet two nights ago required a moderately largo telescope to observe it, but to-night it can easily be seen with an opera glass, having increased 15 times in 48 hours. The activity of the display, which is without a parallel in cometary history, is more extraordinary on account of the very great distance of the comet from the sun, and, should the present increase of light continue, the bright-ness of the object will exceed many times its computed brilliancy.