Chemical factory Gebrüder Gravenhorst

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Johann Heinrich (left) and Christoph Julius Gravenhorst on the frontispiece of the Economic Encyclopedia , Volume 19, 1780

The chemical factory of the Gravenhorst brothers was a company for the manufacture of chemical and pharmaceutical products in Braunschweig . It was founded in 1759 and ceased operations in the early 19th century. The Gravenhorstsche factory was the first factory for ammonium chloride in Germany. In publications in the field of chemical and pharmaceutical history, it is often referred to as the first chemical factory in the German-speaking area.

Company history

The company was founded by the brothers Johann Heinrich Gravenhorst (1719–1781) and Christoph Julius Gravenhorst (1731–1794). Initially, they were supposed to become businesspeople, but intensively studied their own mechanics, hydraulics and chemistry.

In 1759, the brothers acquired the Johannishof , a former property of the Johanniter in the Braunschweig city center , today an area between Kattreppeln and the former post office in Friedrich-Wilhelm-Straße. There they set up production facilities for the manufacture of chemical and pharmaceutical products. From 1762 onwards, salmiak, "Red Brunswick alum " and " Brunswick green " from 1767, Glauber's salt from 1769 and a wound balm called "Balsamus Brunsvicensis" or "Balsamum Brunsvicense" were produced .

Chemical factory of the Gravenhorst brothers
"Plan of the City of Braunschweig" by Albrecht Heinrich Carl Conradi around 1755.
The site of the chemical factory of the Gravenhorst brothers in Braunschweig city center.

None of these products were invented by the brothers. Their achievement consisted rather in the development and factory implementation of economical production processes as well as in an extremely skilful marketing of the products with the means at the time.

The marketing concept was extremely successful. The owners wrote a number of small papers describing the benefits of their products and giving instructions on how to use them. The writings served more commercial than scientific purposes and were printed as general educational, instructive articles in numerous magazines. The same articles were then also distributed to customers and prospects as individual prints. At times the company was in contact with up to 3,000 trade correspondents and in the second half of the 18th century its owners were among the wealthiest citizens of the city of Braunschweig.

After Johann Heinrich's death, the factory was continued by Christoph Julius. After his death, the company was owned by Johann Andreas Christoph Gravenhorst (1768–1833, doctor) and Carl Hermann Julius Gravenhorst († August 12, 1828, manufacturer). In the 1820s the company ceased.

In 1780 Johann Georg Krünitz dedicated the 19th volume of his Economic Encyclopedia to the Gravenhorst brothers. The volume shows the portraits of the brothers on the frontispiece .

Products

While the brothers published numerous fonts for advertising purposes, they kept the manufacturing process top secret. The employees were also sworn to secrecy and paid exceptionally well for this. In addition, it was ensured that no employee had a full overview of the entire production process. Most of the production facilities were built by the owners themselves. Christoph Julius bricked the stoves by hand and often made changes to the systems in night work alone. It is reported that the Gravenhorst brothers did not even let an interested prince into their buildings.

Braunschweig salmiak

→ Main article: Braunschweig salmiak

Salmia (ammonium chloride; NH 4 Cl) was the company's main product. At that time, salmiak was used in dyeing and tannery as well as in tinning , galvanizing and soldering . Until the first salmiac factories were built in England and France , salmiac was mainly imported from Egypt , where it occurs in natural deposits.

In Braunschweig, ammonium chloride was produced from animal and human urine , which was reacted with gypsum ( calcium sulfate ; CaSO 4  · 2 H 2 O) and sodium chloride (NaCl).

The product was purified by recrystallization . A highly concentrated ammonium chloride solution was poured into perforated ceramic molds for crystallization. After crystallization, the ammonium chloride was obtained in a conical block, similar to a sugar loaf . Salmiak in the form of sugar loaf was still called "Braunschweiger Salmiak" after the Braunschweig company was shut down.

Contemporary witnesses reported that the Gravenhorst brothers paid the Braunschweig citizens for the delivery of urine and that the production of salmiac from urine, as happened in the densely built-up inner city of Braunschweig, spread an unpleasant, suffocatingly pungent steam and smell over a wide area.

Brunswick green

→ Main article: Brunswick green

“Braunschweigisches Grün”, a paint based on basic copper salts, was a product derived from salmiac production.

The distribution of the paint was very successful and the product was copied by other manufacturers shortly after its introduction. As early as 1768, the pharmacist Pabytzky from Peine was selling a comparable product under the name "Peinsches Grün".

The Gravenhorst brothers did not publish anything about their own manufacturing process. Other companies that were still producing this product in the 19th century poured copper sheets with a concentrated ammonia solution. After some time of exposure, the "Brunswick green" formed as a green mass that was scraped off.

Glauber's salt

As a by-product of ammonia production, the factory produced Glauber's salt ( sodium sulfate ; Na 2 SO 4  · 10 H 2 O), also under the trade names "Gravenhorst'sches Salz" and "Braunschweig'sches Salz" for pharmaceutical purposes, especially as a laxative , at pharmacies was expelled.

The writer Heinrich Sander (1754–1782) reported after a visit to the factory that the brothers gave their Glauber's salt to many poor people free of charge and the sick Johann Heinrich himself, plagued by hernia and hemorrhoids , “kept his body open” with Glauber's salt.

Red Brunswick alum

Alum ( aluminum potassium sulfate dodecahydrate ; KAl (SO 4 ) 2  · 12 H 2 O) was used in white tannery and dyeing. Because of its astringent effect, alum was used early in medicine to stop bleeding.

In the 18th century, Italian alum ("Roman alum") was considered the best product of its kind, although red iron-containing soil adhered to the crystal surfaces. A colorless, iron-free alum was only obtained by dissolving it in water and filtering it. The reputation of this product was so overwhelming that other manufacturers imitated the coloring and rolled already pure colorless alum in iron oxide before they put it on the market.

The Brunswick company also copied this product by offering alum that was contaminated by cobalt ions as "Roman alum". The cobalt content of the transparent alum crystals gave them a continuous pale red color which, however, could not be removed by dissolving and filtering.

The product was later sold by the Gravenhorst brothers under the trade name “Roter Braunschweiger Alaun”.

Publications (selection)

  • Some news to the public of Gravenhorst's fabric products concerning 1) a completely pure salmiak 2) a sincere red alum 3) a newly invented green Mahler color, called Brunswick green, which is stable in the air and weather 4) a highly purified so-called Glauber's miracle salt or Sal mirabile Glauberi . (1769)
  • Message regarding the medicinal use and benefits of Salis mirabilis Glauberi, or Glauber's salt . (1770, 1775, and 1778)
  • Message to the public, repainting a newly invented green paint, under the name of purified Braunschweigsch Grün . (1771)
  • Further message to the public regarding the Braunschweigische Salmiac . (1772)
  • Expert opinion by the Gravenhorst brothers regarding the use of Glauber's salt against the cattle disease . (1775)
  • Something about the application of the Brunswick balsam in connection with the internal use of the Glauber's salt, against the podagra . (1777)
  • Excerpt from the news relating to Brunswick green, which is only intended to be used for teaching what to do when using the color . (1778)

literature

Individual evidence

  1. ^ A b c Rolf Walter (ed.): History of innovation: Income from the 21st working conference of the Society for Social and Economic History, March 30th to April 2nd, 2005 in Regensburg . F. Steiner, Stuttgart 2007, p. 189, ISBN 978-3-515-08928-9 .
  2. ^ A b c d e Heinrich Sander : Description of his travels through France, the Netherlands, Holland, Germany and Italy - Second part . Friedrich Gotthold Jacobäer, Leipzig 1784, p. 223 f.
  3. ^ Friedrich Knoll : Braunschweig and surroundings . Göritz, Braunschweig 1881, p. 146.
  4. ^ Carl Philipp Ribbentrop : Complete history and description of the city of Braunschweig . Volume v2, Braunschweig 1779, p. 142.
  5. ^ Gabriele Beisswanger: Pharmaceutical supply in the 18th century: the city of Braunschweig and the rural districts in the Duchy of Braunschweig-Wolfenbüttel . Deutscher Apotheker-Verlag, Braunschweig 1996, p. 180, ISBN 3-7692-2023-4 .
  6. ↑ a b Karmarsch
  7. ^ Karl Heinrich Kaufhold (ed.): The economic and social history of the Braunschweigisches Land from the Middle Ages to the present: Early modern times. Olms, Hildesheim 2008, p. 788f, ISBN 978-3-487-13597-7 .
  8. ^ Government sheet for the Kingdom of Bavaria . Munich 1831, p. 715.
  9. ^ August Friedrich Wilhelm Crome : Geographical-statistical representation of the state forces of all the countries belonging to the German confederation . III. Part. Gerhard Fleischer, Leipzig 1827, p. 27 .
  10. ^ Johann Georg Krünitz: Oekonomische Encyklopädie , Vol. 19, Verlag Joachim Pauli, Berlin 1780.
  11. ^ Justus von Liebig : Handbook of Pharmacy . Volume 1, 5th edition, CF Winter, Heidelberg 1843, p. 245.
  12. ^ Johann Anton Heinrich Nicolai: Floor plan of the medical police . Nicolaische Buchhandlung, Berlin 1835, p. 401.
  13. ↑ a b c General Encyclopedia for Merchants and Manufacturers . 3rd edition, Otto Wigand, Leipzig 1838, p. 160.
  14. ^ Friedrich F. Zincke: The new general resin magazine . Vol. 1, Christoph August Reussner, Blankenburg 1768, pp. 114–118.
  15. ↑ Ernst Horn : Handbook of practical drug theory for physicians and surgeons . 2nd edition, Oehmigke the Younger, Berlin 1805, p. 646.
  16. ^ Johannes Leunis : School Natural History - Third Part . 4th edition, Hahn'sche Hofbuchhandlung, Hanover 1870, p. 189.
  17. ↑ Christoph Schümann: The share of German pharmacists in the development of technical chemistry between 1750 and 1850 . Peter Lang, Frankfurt am Main 1997, p. 117, ISBN 3-631-48212-4 .
  18. ^ A b Justus von Liebig: Handbuch der Pharmacie . Volume 1, 5th edition, CF Winter, Heidelberg 1843, pp. 381f.

Coordinates: 52 ° 15 ′ 43 ″  N , 10 ° 31 ′ 19 ″  E