Carbon filament lamps

Kohle,/. coal charcoal carbon, kohlebeheizt, a. heated with coal, coal-fired. Kohle-chemie, /. coal(tar) chemistry, -druck, m. Photog.) carbon print, -fadenlampe, /. carbon-filament lamp, -feuerung, /. heating with coal coal furnace, kohlefrei, a. carbon-free. 

The carbon filament lamp vAiich was developed in parallel at the beginning of this century was always several times as expensive in use as an Auer incandescent mantle. As a result, this first use of the rare eaurth elements achieved great economic success and thanks to his capabilities Auer von Welsbach played a major role in this worldwide achievement. He was in the position to survive the extraordinarily corplicated and obstinately pursued patent battles. 

An absolute method for measuring intensities is to use a calibrated thermopile, bolometer or radiometer and galvanometer system the first of these is the most suitable. Calibration may be carried out at the National Physical Laboratories and The National Bureau of Standards, or by using one of their carbon filament lamps. The thermopiles consist of a bank of interconnected fine-wire thermocouples (Fig. 47). One circuit uses a photoelectric amplifier for the measuring galvanometer (Fig. 48) The image of a tungsten filament F, is projected onto a photo-... 

Hence if we observe a thin layer of the liquid, it appears to be blue, whereas thicker layers are red. Should the intensity of the incident colors change, the color of the solution will also be different. Thus if I d = 100 and /blue = 30, then for e = 1, /abiiie = 15 and /Ored = 80. Therefore the red color predominates, and the solution is colored red. Actually when we observe the solution in a room illuminated by a carbon filament lamp instead of by daylight (much blue light), the color changes from blue to red. 

Originally, each country had its own, and rather poorly reproducible, unit of luminous intensity. Only in 1909 some efforts to unify the luminous intensity appeared by the international candle based on carbon filament lamps. However, Germany, at the same time, stayed with the H er candle which is equal to ca. 9/10 of an international candle. 

To people used to candles and parafRn lamps, the long-lasting and odourless light of the incandescent mantle seemed like a miracle. The carbon filament lamp, invented by Edison in 1879, was no serious threat to Auer s light, as the new lamp was very expensive to use. In fact Auer himself started to develop Edison s idea, and in 1893 he was granted a patent for the osmium filament lamp. 

The traditional carbon filament lamp, called a GLS (general lighting service) lamp, is hopelessly bad in energy-efficiency terms, producing only 14 lumens of light output for every electrical watt input. Fluorescent tubes and CFLs produce more than 40 lumens of light output for every electrical watt input. 

Niobium and tantalum suddenly received considerable attention about the year 1905 as possible materials for the filaments of incandescent electric lamps in place of the carbon filament then in use The metals were then prepared in the pure state for the first time by Dr Werner von Bolton,6 and their properties were examined. Niobium was found to be unsuitable for the purpose in view, but tantalum proved to be satisfactory. Tantalum lamps were manufactured in large quantities between the years 1905 and 1911, when the metal was displaced by the electrically more efficient tungsten. 

A solution or suspension of the acid (1 mmol) in carbon tetrachloride (75 ml) containing DIB (0.55 mmol) and iodine (0.5 mmol) was irradiated with two 100 W tungsten-filament lamps for 45 min at reflux temperature. Another portion of DIB (0.55 mmol) was then added and irradiation was continued for 45 min at reflux. The reaction mixture was washed with dilute sodium thiosulphate and water, concentrated and chromatographed (silica gel column, 9 1 hexanes-ethyl acetate) to afford the alkyl iodide. Several steroidal acids with the carboxyl group attached at a 1° or 2° carbon atom gave the corresponding iodides in good yields. Acids with a 3° a-C instead of the iodide afforded alkenes similarly, alkenes were formed with a fivefold excess of DIB in the presence of cupric acetate. Aromatic acids also underwent iododecarboxylation, in moderate yields very effective was the otherwise difficult transformation of 1,8-naphthalenedicarboxylic acid to 1,8-diiodonaphthalene (80%) [68]. Cubyl and homocubyl iodides were also prepared in excellent yield [69]. 

As a matter of historical interest, it should be mentioned that Edison was not the inventor of the filament lamp, although this has been frequently urged. Actually, in i860, Sir Joseph Swan obtained a glow in a carbon filament in vacuo and by 1878 he had perfected his filament lamps and placed them on show in this country. At this time Edison s lamp was only in the laboratory stage. This is not to minimise in the slightest Edison s work. But fact is fact. 

The development of viscose was largely the work of two English cellulose chemists. Cross and Bevan, who, with Beadle, received a patent on the process in 1892 [116]. In 1893, they sent a sample of viscose solution to Switzerland, where Charles H. Steam had been working with Charles F. Topham on carbon filaments for electric lamps. They had worked with nitrocellulose rayon for this purpose and had a small lamp factory for utilizing the carbon filaments. 

The mid-infrared soures can be used in the far-infrared region down to frequencies of approximately 100 wavenumbers. Below this region a high-pressure mercury vapor lamp can be used, provided the ultraviolet and visible frequencies are removed by the suitable optical filter. This filter is usually carbon impregnated polyethylene. In the near-infrared region a tungsten filament lamp functions well as the source. 

---