Auch "Krakelee" oder "Krakelüren". Bezeichnung für feine Risse bei der Edelmetallbearbeitung und bei Edel- und Schmucksteinen. Man spricht von "Krakelierten Steinen". Eignen sich zum Behandeln (Farbverändern) durch Färben sehr gut. Finden sich auch bei Ölbildern, Glas und Porzellanobjekten.
The process whereby heavy molecules of naphtha or petroleum are broken down into hydrocarbons of lower molecular weight (especially in the oil-refining process).
Reaction in which a large alkane molecule is broken down by heat into a smaller alkane and a small alkene molecule. The reaction is carried out at a high temperature (600şC or higher) and often in the presence of a catalyst. Cracking is a commonly used process in the petrochemical industry.
It is the main method of preparation of alkenes and is also used to manufacture gasoline from the higher-boiling-point fractions that are obtained by fractional distillation (fractionation) of crude oil.