He served as Director and briefly as Vice-Chancellor of the Institute of Chemistry at the University of Veterinary Medicine Hanover. His published works on organic chemistry were of importance to veterinarians, medical students and pharmacists. He was also an accomplished alpinist and chairman of the Hanover section of the German-Austrian Alpine Association. Karl Arnold was the son of chemist Georg Friedrich Arnold of the village of Uffenheim. From 1851 to 1859 Georg Friedrich Arnold operated a pharmacy in the lower floor of the town hall. The family then moved to Ansbach, where Georg Friedrich Arnold became the Bavarian court pharmacist. After attending the local gymnasium Karl Arnold began training as a pharmacist with his Father, also working as an assistant apothecary in pharmacies in Zofingen, Hamburg, Frankfurt am Main and Magdeburg. In 1875 he began formal studies in pharmacy at the University of Munich, receiving his license as a pharmacist in 1876. Arnold worked with Max Joseph von Pettenkofer, professor of hygiene at Munich. During his time in Munich, he became a member of an academic singing association, the Akademische Gesangverein (AGV) München in the Sondershäuser Verband. Arnold went on to study chemistry and physics at the University of Tübingen, where he worked with Julius Lothar Meyer. Meyer proposed models for the periodic table of elements in 1860 and 1868, and Arnold himself proposed a model for the periodic table in 1885. In 1877 Arnold passed the state teaching examinations for natural science. He completed his doctoral thesis with Robert Wilhelm Bunsen at the University of Heidelberg, studying inorganic and physical chemistry. Arnold received the degree of Doctor of Philosophy in 1878, at the age of 25. Karl Arnold worked as a pharmacist to fulfill his military service. He was an assistant in Würzburg and a lecturer in Gerstungen. On May 1, 1880, Arnold began to work at the Königliche Tierarzneischule (Royal Veterinary School) in Hanover (now the University of Veterinary Medicine Hanover). Initially he was a lecturer, demonstrator and tutor in chemistry and physics, earning "1500 M. Remuneration, freier Wohnung, Licht und Heizung in der Anstalt" ("1500 M. Remuneration, free apartment, light and heating in the institution"). When chairman Karl Begemann fell ill in 1883, Arnold took over his chemistry courses.