Germain Henri Hess (; 7 August 1802 – 30 November 1850) was a Swiss-Russian chemist and doctor who formulated Hess's law, an early principle of thermochemistry. Early life and education Hess was born on 26 July (7 August) in Geneva, Switzerland. His father was an artist and in 1805 moved the family to Russia to work as a tutor to a rich family. His Swiss-born mother was a tutor as well and Hess had the benefit of learning German and French at home. In 1817, his family moved to Dorpat, Russian Empire (now Tartu, Estonia), where he went to a private school for two years, and then to Dorpat Gymnasium, which he finished in 1822. In autumn of the same year Hess studied medicine at the University of Dorpat. During that time, the chemistry department was responsible for the Chemistry courses of the Medicine and Pharmacy departments and Professor Gottfried W. Osann was giving the lectures in German (an obvious advance for Hess). Under Osann's supervision, Hess made chemical analyses, but also had an interest in the lectures of Professor of Physics Georges-Frédéric Parrot and Professor of Mineralogy Moritz von Engelhardt. Hess graduated with honors from Dorpat University receiving a doctor of medicine degree with his dissertation entitled Something about Curative Waters, Especially Those in Russia. He qualified as a physician in 1825. By application of Professors Osann and Engelhardt, Hess was sent to Sweden, to visit Swedish chemist Jöns Jakob Berzelius. After this meeting Hess turned once and for all to chemistry. On his return to Russia, Hess joined an expedition to study the geology of the Urals before he was appointed a doctor at Irkutsk. According to the regulations of that time, new doctors had to practice at a Russian frontier town after having graduated. Hess went to Irkutsk in August 1826. Contributions to chemistry In 1830, Hess took up chemistry full-time, researching and teaching, and later became an adjunct professor of Chemistry at the St. Petersburg Academy of Sciences. His most famous paper, outlining his law on thermochemistry, was published there in 1840. His principle, a progenitor for the first law of thermodynamics, came to be called Hess's law. It states that in a series of chemical reactions, the total energy gained or lost depends only on the initial and final states, regardless of the number or path of the steps. This is also known as the