Wikipedia:Reference desk/Archives/Miscellaneous/2020 October 27

= October 27 =

La nuit de Walpurgis by Constantin Nepo
Hi, I have been looking everywhere for more information about the painting La nuit de Walpurgis by Constantin Nepo, like time and location. If anyone knows of any site or info about it, I’d really appreciate it.  Miss Bono  [hello, hello!]  03:03, 27 October 2020 (UTC)
 * I don't know if this is helpful, but the full name of the artist in Russian is Константин Константинович Непокойчицкий (Moscow, 1914 – Paris, 30 December 30 1976), shortened to Константин Непо. He was the husband of ballerina Yvette Chauviré, who died just four years ago. --Lambiam 09:37, 27 October 2020 (UTC)
 * The information above is confirmed on other sites (see here, e.g. ). Nepo was active starting in the early 1920s, but the work you mention appears to be more recent, from its style. Lots of reproductions of that work are available on social media sites (mainly Pinterest), but none that give more information about its origins. This snippet from 2011 calls Nepo a "forgotten artist", and mentions that he was  "a choreographer, painter of theatre scenery, theatre producer, actor, night-club artist in Saint-Germain-des-Prés, guitarist, singer, painter, and a friend many famous persons such as Picasso or Giacometti, as well as Yvette Chauviré's partner." Another site mentions he was of Romani (gypsy) background, and was sometimes called "Prince Nepo". He doesn't seem to have any works in major museums, so I expect that the painting in question belongs to a private collector. Most of his work appears to be in the orientalist tradition, and he seems to have been active in Morocco at some point, because a number of his works feature Moroccan subjects. By the way, the subject of the painting Walpurgis Night is from the opera Faust by Charles Gounod, itself inspired by the play by Goethe. It could thus have been produced as part of the scenery for a staging of the opera.  Xuxl (talk) 13:55, 27 October 2020 (UTC)
 * Digging deeper, I find that the Walpurgis Nacht section of Gounod's opera has often been staged as a self-standing ballet. It makes it even more likely that the painting was produced as an illustration for a production of this ballet, since Nepo's works for the theater were mainly for ballets (which is not surprising given his spouse was a famous ballerina). This 1966 article from Le Monde confirms that Yvette Chauviré had danced that ballet at the Opera de Paris some years before. This article  mentions that it was staged at the Opéra de Paris in 1935 and 1958. Yvette Chauviré is not listed as one of the dancers in 1935, but it's a candidate as she was already a member of the Opéra's dance company by that time. The 1958 performance was by a visiting Russian troupe, so it's unlikely they would have commissioned a Parisian artist to produce scenery for that. Xuxl (talk) 16:54, 27 October 2020 (UTC)
 * The list of performances at the Paris Opéra skips a 5th performance between 1935 and 1958, unless "(6e)" is a typo for "(5e)". If a painting was used as a backdrop for the 1958 staging of the ballet, it would have been too large for the visiting Bolshoi troupe to have brought it with them, in which case it was most likely locally produced. Since Nepo was not only a Russian painter but also a muralist and had a connection to ballet, he would then, I think, have been well positioned for being commissioned for this. --Lambiam 13:07, 28 October 2020 (UTC)
 * Thank you very much! Miss Bono

chemical
What is the absolute method classification means and wich analytical techniques belongs to this group? How we can get the concentration from the meassured quantities? — Preceding unsigned comment added by فزييلنسوفب (talk • contribs) 15:07, 27 October 2020 (UTC)
 * I'm not sure what you mean by the first question? I've never heard of the "absolute method classification".  Your second question, how to calculate concentration; there are several methods of doing so, as there are several different ways to express concentration.  If you read that Wikipedia article I just linked, it goes through SEVERAL different ways to express and calculate concentration, I won't list them all here.  -- Jayron 32 17:31, 27 October 2020 (UTC)


 * The McGraw-Hill Dictionary of Scientific & Technical Terms, 6th edition, has this definition:
 * absolute method [′ab·sə‚lüt ′meth·əd]
 * (analytical chemistry)
 * A method of chemical analysis that bases characterization completely on standards defined in terms of physical properties.
 * One of the citations below this definition, under the heading "References in classic literature", contrasts (1H-NMR) spectroscopy as an absolute method with IR spectroscopy as a relative method; the same source also uses the terminology of comparative method. Apparently, these terms are used by some authors in a classification of analytical techniques. --Lambiam 15:37, 28 October 2020 (UTC)
 * Thanks! It's been a few decades since I was a working chemist; I worked a bit in organic synthesis and a bit in a mass spec lab, and a bit in a food science lab, at the time, and only for a short while anyways.  Makes sense!  -- Jayron 32 15:46, 28 October 2020 (UTC)