FLATS 401 



The fact of the increase of the brilliancy and whiteness of flame by the development 

 and ignition of solid matter in its bosom, illustrates many curious phenomena. We 

 can thus explain why olefiant gas affords the most vivid illumination of all the gases ; 

 because, being surcharged with carbon, this is deposited in the middle of the flame, 

 as it would bo in an ignited porcelain tube, whereby its solid particles first get ignited 

 to whiteness, and then bum away. 



The explanation given above was originally advanced by Sir H. Davy, and has, 

 until recently, been universally accepted by chemists and physicists. Dr. Frankland 

 has, however, brought forward a body of evidence tending to show that the presence of 

 incandescent solid particles is by no means essential to the luminosity of a flame. 

 Indeed, many flames of high illuminating power cannot possibly contain solid par- 

 ticles ; thus, when the vapour of bisulphide of carbon is burnt in nitric oxide gas, it 

 produces a dazzling light, yet without the presence of any solid matter. Frankland 

 maintains that the luminosity of a flame is directly connected with the density of the 

 burning vapours. He finds that dense vapours and gases become luminous at much 

 lower temperatures than do those of less density ; and that a rare gas, when not 

 luminous at a given temperature under ordinary atmospheric pressure, may become so 

 when suddenly compressed. The passage of electric sparks through different gases 

 produces an intensity of light varying with the density of the gas. With respect to 

 ordinary flames, it is believed that glowing particles of precipitated carbon are not 

 the true source of luminosity, and that soot is far from being a deposit of mere carbon. 

 Frankland maintains that ' incandescent particles of carbon are not the source of light 

 in gas and candle-flames, but that the luminosity of these flames is due to radiations 

 from dense but transparent hydrocarbon vapours.' On the Source of Light in 

 Luminous Flames, Proc. Roy. Inst., June 12, 1868. 



In the blowpipe flame from an oil-lamp or a candle, the inner blue flame has the 

 greatest heat, because there the combustion of the whole fatty vapour is complete. 

 The feeble light of burning hydrogen, carbonic oxide, and sulphur, may, upon the 

 principles above expounded, be increased by simply placing in them a few particles of 

 oxide of zinc, slender filaments of amianthus, or fine platina-wire. It is now many 

 years ago since Dr. Ure demonstrated, in his public lectures in Glasgow, that by 

 narrowing the top of a long glass chimney over an argand flame either from oil or 

 coal-gas, the light could be doubled, at the same cost of material. The very tall 

 chimneys used by the lamp-makers are wasteful, as they generate a strong current 

 of air, and the combustion of the solid matter is carried on with great rapidity. With a 

 narrow chimney of half the length we can have nearly as good a light, and save 30 

 per cent, of the oiL See BLOWPIPE ; LAMPS. 



FXi ANDERS BRICKS, commonly called Bath bricks. These are made in large 

 quantities at Bridgewater, from the silty clay deposited in the estuary, which contains 

 a large proportion of fine sand. These bricks are much used for domestic purposes, 

 also in making founders' cores, and for polishing some steel articles. 



FIiANNEIi. A plain woollen stuff of a rather open and slight fabric. 



Wales is the country in which flannel was originally made, and the Welsh flannel 

 is still held in much estimation. Hand labour is rarely employed in the production 

 of Welsh flannel ; and, though it is not so cheap as some others, the quality and finish 

 of this fabric generally cause it to be preferred for vests worn next the skin and 

 similar purposes. Flannels are now made more extensively at Eochdale than in any 

 other part of the world. In that neighbourhood the manufacturers produce the greatest 

 variety of widths, finish, and substance, viz., the thin, the medium, the thick, double- 

 raised, and swanskin. Saddleworth produces the so-called Saxony flannels, which are 

 much admired ; and some varieties are produced at Leeds, and finished the natural 

 colour of the wool. In the West of England flannels are made, but not extensively ; 

 and in Ireland a few varieties of low flannels and coatings, called Galways, are manu- 

 factured from Irish-grown wool. See WOOLLEN- MANUFACTURES. 



FLASHINGS. Pieces of lead or other metal let into the joints of a wall so as to 

 lap over the gutters, and prevent the splashiugs of rain from injuring the internal 

 work. When glass is coated with a thin layer of coloured glass it is said to be 

 ' flashed/ and the operation is called ' flashing.' 



FLASK. In foundries, a shallow iron frame, without top or bottom, used for 

 moulding. The lower flask is called a drag. See FOUNDING. 



FI.AT. The name of a river boat, usually flat-bottomed, and carrying from 80 to 

 1 20 tons. This term is also applied to baskets in which butter is now sent from all 

 parts of the country to the London markets. 



FLAT ROBS. In mining, a series of rods for communicating motion from the 

 engine, horizontally, to the pumps or other machinery in a distant shaft. 



FLATS. A mining term. Flats are the decomposed parts of limestone strata, 

 and often contain deposits of lead ore and other minerals, all of which are spread out 



VOL. II. D D 



