The Spark Discharge

It is well known that most of the gaseous hydrocarbons of the aliphatic series when exploded with an excess of oxygen are converted into the end-products of combustion, carbonic acid and water. This fact is made use of in quantitative gas analysis. The combustion is often not complete intermediate products can be obtained if we start with hydrocarbon derivatives instead of the hydrocarbons themselves. 

Berthelot gave a comprehensive exposition of the results known at that time on the effect of the spark, discharge upon the formation and decomposition of carbonic acid and hydrocarbons and the herewith occurring equilibrium phenomena (Berthelot, Essai de M6canique Chimique II, 336-362, Paris, 1879). 

Methane.—The induction sparks decompose this substance into carbon and hydrogen (Hofmann1 and Buff), which fact Dalton had already observed. 

Berthelot2 obtained hydrogen, carbon and acetylene. If the latter is continually gotten rid of, the greater part of methane can be converted into acetylene, otherwise the latter is decomposed and changed in a complex manner. 

Methane is also produced by the reaction of carbon monoxide with hydrogen under the influence of the induction spark 

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Section 5.4.1 described explosions in storage tanks, and Section 13.3 described explosions in tank trucks, ignited by static sparks. The static was formed by the flow of a nonconducting liquid, and the spark discharges occurred between the body of the liquid and the grounded metal containers (or filling arms). 

The energy E (joules) of the spark discharge from a condenser of capacity C(micro-farads) charged to a potential V (volts), assuming negligible losses is ... 

The visible portion of the spark spectrum between tantalum electrodes is very weak, and the individual lines are measureable only with difficulty.11 The lines between A=2000 and A=4700 in the spectrum of the spark discharge under water are the same as in air, unlike most other metals.12... 

Hot Spots. Combustion-Chamber Deposits) Surface ignition is the initiation of a flame front by any hot surface other than the spark discharge prior to the arrival of the normal flame front. The flame front or fronts so established propagate at normal velocities. This phenomenon can be further subdivided into preignition and postignition. 

J. Pllicker and J. W. Hittorf also showed that with a condensed discharge, the vacuum tube glows with a white light. This gives a line spectrum which is identical with that of the spark discharge, but has no relation with the band spectrum just indicated. These observations were confirmed by A. Wiillner,... 

No very accurate measurements of the temperatures occurring in the spark discharged are available, great difficulties... 

Ethylene is decomposed by the spark discharge into its elements (Dalton, Hofmann, and Buff2). According to Wilde,3 acetylene is first formed, and is then decomposed into its elements, Besides, according to Thinard and Berthelot,4 a fluid and solid product are produced. 

The emission spectra obtained by an electric discharge through the gas under a reduced pressure and by the spark discharge are of a complex nature. ... 

The most common, and most voluminously produced, hot-wire detonator is the electric blasting cap. The history of these devices seemed to start in England in 1745, when a certain Dr. Watson of the Royal Society of England demonstrated that black powder could be ignited by the spark discharge from a Leyden Jar. 

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