Emission of Sparks

Fire always requires a substrate it cannot exist without air, moisture, and earthy vapors. The breath increases the flame, lamps consume more oil in a draft, and wood burns more rapidly. Coal and wood burn only in a draft, because they have narrow pores that the draft opens and makes more pervious to the fire. Flame is purer when it contains no aqueous or earthy components that lead to smoke and vapor. 

Wohler also had problems with chemical experiments when he was at school, as is reported by Kahlbaum (F. Wohler, Ein Jugendbildnis in letters to Flermann von Meyer, 1900)  

Operations requiring larger quantities of heat were carried out in the courtyard in the laundry, and an old graphite furnace donated by the master of the mint, Bunsen (a relative of the famous chemist), served as an oven but one fine day in the course of one of the experiments this improvised fireproof laboratory also went up in flames. 

Safety glasses and protective gloves should be worn. The sparkler should be ignited at a distance of at least a meter from the reaction flask in order to ensure that no sparks can fly into the flask prior to the experiment. Care must be taken to make sure that neither hands nor face are directly above the flask when the sparkler is thrown in. 

1-L beaker, 250-mL Erlenmeyer flask, dropping pipette, long-stem funnel, fire-resistant support 50 x 50 cm, sparkler, protective gloves, safety glasses. 

---

Screening test (VDl 2263, Part 1 [1]) Burning index 5 (burning with an open flame or emission of sparks). 

The focus of this section is the emission of ultraviolet and visible radiation following thermal or electrical excitation of atoms. Atomic emission spectroscopy has a long history. Qualitative applications based on the color of flames were used in the smelting of ores as early as 1550 and were more fully developed around 1830 with the observation of atomic spectra generated by flame emission and spark emission.Quantitative applications based on the atomic emission from electrical sparks were developed by Norman Lockyer (1836-1920) in the early 1870s, and quantitative applications based on flame emission were pioneered by IT. G. Lunde-gardh in 1930. Atomic emission based on emission from a plasma was introduced in 1964. 

This is a transient discrete electric discharge which takes place between two conductors which are at different potentials, bridging the gap in the form of a single ionization channel (Plate 4). Based on light emission measurements of sparks with symmetrical electrode geometry, the energy is dissipated approximately uniformly along the channel. This is in contrast with asym-... 

A. Thomas and G.T. Williams. Elame noise Sound emission from spark-ignited bubbles of combustible gas. Proc. R. Soc. Lond. A, 294 449 66,1966. 

Only arc/spark, plasma emission, plasma mass spectrometry and X-ray emission spectrometry are suitable techniques for qualitative analysis as in each case the relevant spectral ranges can be scanned and studied simply and quickly. Quantitative methods based on the emission of electromagnetic radiation rely on the direct proportionality between emitted intensity and the concentration of the analyte. The exact nature of the relation is complex and varies with the technique it will be discussed more fully in the appropriate sections. Quantitative measurements by atomic absorption spectrometry depend upon a relation which closely resembles the Beer-Lambert law relating to molecular absorption in solution (p. 357 etal.). 

A technique that utilizes a solid sample for light emission is spark emission spectroscopy. In this technique, a high voltage is used to excite a solid sample held in an electrode cup in such a way that when a spark is created with a nearby electrode, atomization, excitation, and emission occur and the emitted light is measured. Detection of what lines are emitted allows for qualitative analysis of the solid material. Detection of the intensity of the lines allows for quantitative analysis. 

Gives a forceful emission of fire and sparks especially when used in a tube with a choke or nozzle. 

Although it is known that the colour of black body radiation is only dependent upon temperature, sparks have colours that are also dependent upon the type of emitting material. However, the form of the radiance curves does not relate exactly with known molecular energy transitions. This suggests that the mechanism of emission in excess of black body radiation is not yet fully established. It is possible that some emission bands only become active when the metal oxide particle is molten, or that the energy is dissipated simply via collisions with other molecules rather than the emission of photons. 

Thus, although the colour of sparks is dependent upon flame temperature and may be similar to that of black body radiation, the overall colour effect can include contributions from atomic line emissions, from metals (seen in the UV and visible regions of the electromagnetic spectrum), from band emissions from excited oxide molecules (seen in the UV, visible and IR regions) and from continuum hot body radiation and other luminescence effects. So far as black body radiation is concerned, the colour is known to change from red (500 °C glowing cooker... 

Emission spectrometry (ES). Emission spectrometry is based on the excitation of an element to an upper electronically excited state, from which it returns to the ground state by the emission of radiation. As discussed in Chapter 3, the wavelength emitted is characteristic of the emitted species, and, under the approximate conditions, the emission intensity is proportional to its concentration. Means of excitation include arcs and sparks, plasma jets (see ICP), and lasers. 

At very low temperatures carbon disulphide solidifies to a crystalline mass which melts at —112-97° C.7 The crystallisation may be accompanied by the emission of small sparks.8 At —185° C. the crystals are tetragonal.9 The heat of fusion, deduced from determinations of the freezing-points of dilute solutions in certain organic solvents,10 is 660 calories. The fusion curve showing the connection between pressure and melting-point has been determined.11... 

This research effort has demonstrated the capability of spark source and thermal emission mass spectrometry for determining the fate of trace elements in coal-fired, central power plants. Additionally, isotope dilu-... 

Production of Ions. Several methods are used (11 by bombardment with electrons from a heated filament (2 by application of a strong electrostatic field (field ionization, field desorption) Ot by reaction with an ionized reagent gas (chemical ionization) (4 by direct emission of ions from a solid sample that is deposited on a heated filament (surface ionization) (SI by vaporization from a crucible and subsequent electron bombardment (e.g.. Knudsen cell for high-lcmperalure sludies id solids and (6) by radio-frequency spark bomhardmenl of sample fur parts-per-biliion (ppb) elemental analysis of solids as encountered in metallurgical, semiconductor, ceramics, and geological studies. Ions also are produced by photoion izution and laser ionizalion. 

A. A. Quader, Why Intake Charge Dilution Decreases Nitric Oxide Emissions from Spark Ignited Engines, SAE 710009, Society of Automotive Engineers, Warrendale, Pa., 1971. 

Many different filter designs have been the subject of experimental studies on diesel soot combustion. In the early investigations, structured honeycomb filters made from cordierite, such as those applied for the three-way catalyst for the reduction of spark ignition engine gas emissions, were the focus of the experimental studies [29-39]. The experimental results with these filters were not promising, because the cordierite honeycomb filter did not withstand the thermal stress. Temperature peaks of almost 1200 °C were measured, after which the ceramic structure was partly melted or totally destroyed [29, 40],... 

---