In the analysis of solids, often the first step is to get the analyte into solution in some form. Sometimes, solids are heated in the presence of acids (acid digestion) or molten salts (sample decomposition through fusion according to this source). These methods combined are call "Aufschluss" in German (roughly translated unlocking). There is a joke in the qualitative analysis teaching lab that for particularly difficult samples, you use the "Assistenten Aufschluss", i.e. you have to cheat and beg the T.A. to tell you what is in your sample.

Is there a technical term in English or in other languages?

  • 3
    $\begingroup$ I don't think there is a single English equivalent word in analytical chemistry that would match Aufschluss. I feel this is more colloquial although Duden describes it for dissolution. At best it would be dissolution, decomposition methods or digestion methods. For example, there is a book "Decomposition methods in analytical chemistry." which is a German translation of "Aufschlussmethoden der anorganischen und organischen Chemie, published in 1972 by Verlag Chemie GmbH, Weinheim/Bergstr. $\endgroup$
    – M. Farooq
    Oct 7 '21 at 21:45
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    $\begingroup$ There are English translations, but you lose the wordplay. The joke only works because the typical meaning of Aufschluss is to find out about something, to obtain clarifying information. Which is precisely what you would be doing by asking the TA. Then, there is the more obscure technical meaning of Aufschluss, which is to solubilize or dissolve solids into solution. Note the two suitable translations given in the previous sentence. Unfortunately, in English, neither have dual meanings of "enlighten", "investigate", "reveal", etc. $\endgroup$
    – Cody Gray
    Oct 10 '21 at 4:51

«Digest» (the result) and «digestion» (the process) are seen again and again (e.g., already in the abstract here, or revising the state of the art here (first page, right hand column). Speaking of this university, «Freiberg digestion» is a common term, too (cf. e.g., Sundermayer in ACIE (p. 228/229). If the intermediate melt is alcaline, «alkali fusion» is used, too.

«Digest» (like in «Reader's digest») applies well on ores and biological samples, though the concept applied on cells seems more often called «lysis» instead.

«Digestion» equally applies well for French, for which Le Petit Noveau Robert (1996, print edition; a one-volume orthography dictionary for the general use, not tied to chemistry) explicitly states the chemical relevance of this noun:

«2. (chim) Dissolution d'une substance dans un liquide à haute température ou extraction de certains élements de cette substance.»

which translates into

  1. (chemistry) Dissolution of a substance in a liquid of high temperature, or extraction of certain components of this substance.)

backed nicely by the entry in the dictionary of the Academie Française. Voilà.

  • $\begingroup$ I don't understand «dal», nor found yet a reference for this word; is it perhaps a typo? «Crumbling» sounds for me like a mechanical action (like mortar and pestle, crushers and stamp mills). But it is true, physicians call digestion all and every action between entry and exits of our body (though with discern between mechanical digestion, e.g. by teeth; and chemical, e.g., by endogenous substances and the many organisms living in the digestive path). $\endgroup$
    – Buttonwood
    Oct 10 '21 at 16:02

It's not a special case and there is no problem in translating the German term “Aufschluss” into English once the context is given, i.e. disambiguation is performed. In the absence of one there cannot be a definitive translation since the word has multiple meanings (Duden lists six) allowing for the wordplay as with your example with TA.

Staying in the realm of chemistry and biology, “der Aufschluss” generally refers to a process of transferring to a soluble state that is convenient for processing. The most universal English term in this context would likely be “dissolution”, followed by more field-specific ones [1, p. 16]:

Aufschluss chem (in Lösung bringen) dissolution, digestion; disintegration, decomposition; dissociation, solubilization; lysis; fractionation; maceration; (paper) cooking, pulping.

Interestingly enough, “Aufschluss” hasn't been borrowed verbatim into other languages as, for example, “Anschluss” has been: another example of how important the choice and use of separable prefixes in German are.


  1. Cole, T. C. H. Wörterbuch Der Chemie / Dictionary of Chemistry (Deutsch/English), 2., überarbeitete und erweiterte Auflage.; Springer Spektrum: Berlin, 2018. ISBN 978-3-662-56330-4.

Maybe there is no exact English translation of the word "Aufschluss". The best translation is something between "dissolution" and "crumble". It is used for extracting an element present in a substance that is insoluble in all known solvents and solutions, like acidic, basic and complex solutions.

Let's take the example of Barium $\ce{Ba}$. This element comes from the mineral $\ce{BaSO4}$, which is insoluble in all aqueous and non-aqueous solutions. The only way to transform it into something soluble is to roast it with an excess of dry $\ce{Na2CO3}$. When heated above $\ce{Na2CO3}$ melting point ($851$°C), the following reaction happens : $$\ce{BaSO4 + Na2CO3 -> Na2SO4 + BaCO3}$$ After cooling, the residual solid mixture is washed with water, and $\ce{Na2SO4}$ gets dissolved, leaving the insoluble $\ce{BaCO3}$. This rection has transformed an insoluble Barium compound into another insoluble Barium compound. But $\ce{BaCO3}$ is more useful than $\ce{BaSO4}$ as it does react with hydrochloric acid, producing : $$\ce{BaCO3 + 2 HCl -> BaCl2 + H2O + CO2}$$ The result of this reaction is a substance that is soluble into water : $\ce{BaCl2}$ The whole process is called "Aufschluss".

  • $\begingroup$ If it is just «dry heat», then it is roasting; a term not only used for coffee and meat. Re $\ce{BaSO4}$, the reduction into sulfide, leaching as a carbonate and reduction seem at least plausible, too, cf. Russian Wikipedia here; but it is a tangential note only. $\endgroup$
    – Buttonwood
    Oct 10 '21 at 16:07
  • $\begingroup$ @Buttonwood. Thank ou for the idea. The word "roasting" seems more appropriate. And the reduction of $\ce{BaSO4}$ into $\ce{BaS}$ by charcoal is also possible. But the odor of $\ce{H2S}$ is repulsive. $\endgroup$
    – Maurice
    Oct 10 '21 at 16:38
  • $\begingroup$ Work with tert-BuSH in stoichiometric quantities during a summer project remains in «strong» memory. But according to a lecture (including samples applied on test stripes) by a representative from Firmenich, scent/odor equally is a question of concentration (e.g. very dilute solutions of skatole convey a rose-like scent, and are used in perfumes [e.g., Peau de Bête]). Eh bien. $\endgroup$
    – Buttonwood
    Oct 10 '21 at 17:03
  • $\begingroup$ @Buttonwood. Right. But $\ce{H2S}$ smells of rotten eggs, whatever its concentration. $\endgroup$
    – Maurice
    Oct 10 '21 at 18:47

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