Acetylene lamp

“ Looked at from one aspect the holder of a fixed apparatus is merely an economical substitute for the wasteful vent- pipe, because it is a place in which acetylene can be held in reserve whenever the make exceeds the consumption in speed. It is perhaps possible to conceive of a large table acetylene lamp fitted with a water- sealed rising holder; but for vehicular purposes the displacement holder is practically the only one available, and in small apparatus it becomes too minute in size to be of much service as a store for the gas produced by after-generation. ”

“ When an acetylene lamp is in good order it will light up slowly with a hissing noise followed by a pure white flame. Should the lamp light up quickly with a yellowish flame, it is a sign of a leak somewhere. ”

“ It should, however, be added that modern forms of the safety lamp, in which the light is surrounded by a stout glass chimney and only sufficient gauze is used for the admission of fresh air and for the escape of the combustion products, appear quite satisfactory when employed in an atmosphere containing some free acetylene. ”

“ Acetylene is a very useful and powerful illuminant when all else fails. It is the nearest artificial approach to sunlight. Petrol gas with an incandescent mantle will be found just as good as ordinary coal gas, while there are many cheap lamps well adapted for its use. If all these alternatives are lacking there is the electric flash lamp working with the dry battery. A tiny metallic filament incandescent bulb mounted within a parabolic reflector will give a light of intense brilliancy. ”

“ In connexion with the smaller amount of heat developed per unit of light when acetylene is the illuminant, the frequently exaggerated claim that acetylene does not blacken ceilings at all may be studied. Except it be a carelessly manipulated petroleum-lamp, no form of artificial illuminant employed nowadays ever emits black smoke, soot, or carbon, in spite of the fact that all luminous flames commercially capable of utilisation do contain free carbon in the elemental state. ”

“ The disfavour with which cycle and motor acetylene lamps are frequently regarded by nocturnal travellers, other than the users thereof, is due to thoughtless design in the optical part of such lamps, and is no argument against the employment of acetylene. ”

“ The light is so actinic, or rich in rays acting upon silver salts, that it is peculiarly useful to the photographer, either for portraiture or for his various positive printing operations. Acetylene is very convenient for optical lantern work on the small scale, or where the oxy-hydrogen or oxy-coal-gas light cannot be used. Its intensity and small size make its self-luminous flame preferable on optical grounds to the oil-lamp or the coal-gas mantle ”

“ It burns with a steady snow-white flame of great brilliancy and high candle power. M. Trouvé, says La Nature, has recently invented a practical lamp for generating and burning acetylene. The reservoir of the lamp is of glass and contains a metallic box in which is placed the calcium carbide. This box is connected with a stopcock, leading to a small gas burner which projects from the top of the reservoir, and is so arranged that as the water in the reservoir is allowed to enter and act on the calcium carbide, acetylene is generated and passes out to the burner where it may be ignited. ”

“ This has an electric light near the end in the oval space; this light [Pg 159] makes it possible to grapple for persons who may have gone down beneath the water.
We have also received from France the account of an invention in the shape of a bicycle lamp in which acetylene is burned. The great difficulty with the use of acetylene has heretofore been that the gas will not burn unless under high pressure, and the receptacles in which the gas is generated could not be so made as to insure them against ex [Pg 160] ploding. ”

“ The efficiency (i.e., the light yielded per pint or other unit volume consumed) of oil-lamps varies greatly, and, speaking broadly, increases with the power of the lamp. But as large or high-power lamps are not needed throughout a house, it is fairer to assume that the light obtainable from oil in ordinary household use is the mean of that afforded by large and that afforded by small lamps. A large oil-lamp as commonly used in country houses will give a light of about 20 candle- power, while a convenient small lamp will give a light of not more than about 5 candle-power. ”

“ Economy apart, no difficulty arises from imperfect combustion or escape of unburnt gas from an outdoor lamp, but in a room the presence of unburnt acetylene must always be offensive even if it is not dangerous; while the combustion products of the impurities--and in a portable generator acetylene cannot be chemically purified--are highly objectionable. It is simply a matter of good design to render any form of portable apparatus safe against explosion (employment of proper carbide being assumed) , for one or more vent-pipes can always be inserted in the proper places ”

“ Regarding somewhat more closely the relative convenience and safety of acetylene and paraffin for the illumination of country residences, it may be remarked that an extraordinarily great amount of care must be bestowed upon each separate lamp if the whole house is to be kept free from an odour which is very offensive to the nostrils; and the time occupied in this process, which of itself is a disagreeable one, reaches several hours every day. Habit has taught the country dweller to accept as inevitable this waste of time, and largely to ignore the odour of petroleum in his abode ”

“ The standard of illumination adopted for the table is one which is only gaining general recognition where incandescent gas or acetylene lighting is available, though in exceptional cases it has doubtless been attained by means of oil-lamps or flat-flame gas-burners, but very rarely if ever by means of carbon-filament electric glow-lamps, or candles. It assumes that the occupants of a room do not wish to be troubled to bring work or book "to the light," but wish to be able to work or read wheresoever in the room they will, without consideration of the whereabouts of the light or lights. ”

“ But the cost of the gas consumed will be high, and actually light could be obtained directly from the gas by means of incandescent mantles at far loss cost than by consuming the gas in a motor for the indirect production of light by means of electric current. Therefore electric lighting, if adopted under these conditions, must be preferred to gas lighting from considerations which are deemed to outweigh those of a much higher cost, and acetylene does not present so great advantages over coal-gas as to affect the choice of electric lighting. ”

“ The light of the acetylene flame has, however, some intrinsic advantages over the light of other artificial illuminants. In the first place, the light more closely resembles sunlight in composition or "colour." It is more nearly a pure "white" light than is any other flame or incandescent body in general use for illuminating purposes. The nature or composition of the light of the acetylene flame will be dealt with more exhaustively later, and compared with that afforded by other illuminants ”

“ There is one respect in which acetylene and other flame illuminants are superior to electric lighting, viz., that they sterilise a larger volume of air. All the air which is needed to support combustion, as well as the excess of air which actually passes through the burner tube and flame in incandescent burners, is obviously sterilised; but so also is the much larger volume of air which, by virtue of the up-current due to the heat of the flame, is brought into anything like close proximity with the light. ”

“ CHAPTER VIII COMBUSTION OF ACETYLENE IN LUMINOUS BURNERS--THEIR DISPOSITION
NATURE OF LUMINOUS FLAMES.--When referring to methods of obtaining artificial light by means of processes involving combustion or oxidation, the term "incandescence" is usually limited to those forms of burner in which some extraneous substance, such as a "mantle," is raised to a brilliant white heat. Though convenient, the phrase is a mere convention, for all artificial illuminants, even including the electric light, which exhibit a useful degree of intensity depend on the same principle of incandescence. ”

“ Even when allowance is made for the difficulties in determining illuminating power, especially when different photometers, different standards of light, and different observers are concerned, it will be seen that these results are too irregular to be altogether trustworthy, and that much more work must be done on this subject before the economy of the acetylene flame can be appraised with exactitude. ”

“ Now the amount of light given by such a gas flame is no greater than is pleasant to the eye; it is true that if we burn five cubic feet of acetylene from a suitable flat-flame burner, a light of two hundred and forty candles is given, but it is unfair to take this ratio as representing the actual relative illuminating value of the two lights, because we neither need a light of two hundred and forty candles, nor is such an amount of light issuing from one burner endurable to the eye. One-foot or one-half foot acetylene burners are used for domestic lighting ”

“ Electric lighting is as superior to other modes of lighting in respect of direct vitiation as of exhaustion of the air, because it does not depend on combustion. Putting it aside, however, light is obtainable by means of acetylene with less attendant vitiation of the air than by means of any other gas or of oil or candles. The principal vitiating factor in all cases is the carbonic acid produced by the combustion. Now one volume of acetylene on combustion yields two volumes of carbonic acid, whereas one volume of coal-gas yields about 0.6 volume of carbonic acid. ”

“ But it was a scarce and expensive material, and so long as it was heated to incandescence in the open air, that is, so long as its heat was fed as other heat is, by oxygen, it was slowly consumed. Platinum is no longer in the field of electric lighting, and the substitute which takes its place in the present incandescent lamp, and which is known as a "filament," is not heated in contact with the air. The experiments and endeavors that brought this result constitute the story of the incandescent lamp. ”

“ Nevertheless, it should be recollected that when the conventional system is retained--useful illuminating effect being sacrificed to absolute illuminating power--acetylene is made to appear cheaper in comparison with all weaker unit sources of light, and dearer in comparison with all stronger unit sources of light than the accompanying table indicates it to be. ”

“ Acetylene has also been used in the United States, Germany, the Argentine, China, Canada, &c., for lighthouse and beacon illumination. Many buoys and beacons on the German and Dutch coasts have been supplied with oil gas mixed with 20% of acetylene, thereby obtaining an increase of over 100% in illuminating intensity. In France an incandescent burner consuming acetylene gas mixed with air has been installed at the Chassiron lighthouse (1902) . The French Lighthouse Service has perfected an incandescent acetylene burner with a 55 mm. ”

“ No other gas which can be produced on a commercial scale is capable of giving, volume for volume, so great a yield of light as acetylene. Hence, apart from the advantages accruing to it from its mode of production and the nature of the raw material from which it is produced, it possesses an inherent advantage over other illuminating gases in the smaller storage accommodation and smaller mains and service-pipes requisite for the maintenance of a given supply of artificial light. ”

“ But where current cannot be had from an electricity-supply undertaking, and it is a question, in the event of electric lighting being adopted, of generating current by driving a dynamo, either by means of a gas-engine supplied from public gas-mains, by means of a special boiler installation, or by means of an oil-engine or of a power gas-plant and gas-engine, the claims of acetylene to preference are very strong. ”

“ No other gas easily produced upon a commercial scale yields as much light, volume for volume, as acetylene. It has the great advantage of being easily prepared from raw material whose yield of gas is considerably greater for a given amount than the raw materials which are used in making other illuminating gases. The simplicity of the manufacture of acetylene from calcium carbide and water gives to this gas a great advantage in some cases. It has served for individual lighting in houses and in other places where gas or electric service was unavailable. ”

“ While the copper and platinum wires readily conduct the current, the carbon filament offers a great deal of resistance to its passage, and for this reason becomes very hot, in fact is raised to white heat or incandescence, which gives its name to the lamp. ”

“ Acetylene is undoubtedly the illuminant most in favour next to electric light, as the light is brilliant enough to illuminate a picture 12 feet in diameter at a distance up to, say, 30 feet from the screen, and this suffices in a large majority of cases, and acetylene is comparatively cheap, and reasonably simple to work. ”

“ None, it is stated, have broken, even when forced much beyond the incandescence they are intended to bear, and, owing to the compensating action of the gasoline, it is anticipated that the lamps will be permanent. The platinum wires supporting the carbon strip are not fused into the glass of the bulb, as has been the case in previous incandescent lamps, but are surrounded by a slightly elastic cement, which it is averred preserves a good joint. The light given by the lamp is but slightly yellow, is quite pleasing to the eye, and is fairly steady. ”