text: Karl Claus was born in 1796 in Dorpat, Livonia Governorate, Russian Empire, as the son of a painter. At the age of four, he lost his father and two years later became an orphan. In 1810, he moved to Saint Petersburg and started working as an assistant in a pharmacy. Although he had not received formal education, at age 21, Claus managed to pass the State exam in the pharmacy at the Military Medical Academy of St. Petersburg, becoming the youngest pharmacist in Russia at that time. Later in 1826, he established his own pharmacy in Kazan.
  In 1821, Claus married Ernestine Bate whom he knew since his youth. They had three daughters born in Kazan and later a son, when they moved back to Tartu.