Christian Friedrich Schönbein – Ozone and Explosives

Christian Friedrich Schönbein

Christian Friedrich Schönbein (1799-1868)

On August 29, 1868, German-Swiss chemist Christian Friedrich Schönbein passed away. Schönbein is best known for inventing the fuel cell (1838) at the same time as William Robert Grove and his discoveries of guncotton and ozone, of which he also coined its name.

Christian Friedrich Schönbein came from a Pietist family, his father was a dyer, postman and accountant. He was apprenticed to a chemical and pharmaceutical firm at Böblingen when he was 13 years old. Due to his hard work and the sufficient scientific skills and knowledge he studied for, Schönbein completed an examination by Karl Friedrich Kielmeyer, professor of chemistry at the University of Tübingen. He then became director of the chemical plant in Hemhofen near Erlangen, whose owner advised him to study.

From 1820 he studied chemistry in Erlangen, where he met Justus Liebig [3] and Friedrich Wilhelm Joseph Schelling, who later financed his studies. Schönbein then accepted a teaching position in chemistry, physics and mineralogy for two years at an educational institution of Friedrich Fröbel in Keilhau near Rudolstadt, before he went to Epsom near London as a teacher.  He then continued his studies at the Sorbonne in Paris, where he studied with Joseph Louis Gay-Lussac,[4] Louis Jacques Thénard and André-Marie Ampère,[5] among others.  He then moved to Stanmore as a teacher before finally becoming a full professor at the University of Basel at the age of 29.

During the separation of the cantons of Basel, he took the side of the city in order to secure the continued existence of the university. To do so, he volunteered to join the Academic Freikorps, with whom he worked for three weeks. This commitment to the city earned him a lot of sympathy. In 1835 he was also granted citizenship of the city of Basel. In Basel Schönbein first dealt with isomerism and chemical passivity (1835). The short immersion of iron in nitric acid made the iron passive. In 1838 Schönbein created a simple fuel cell by washing two platinum wires in hydrochloric acid with hydrogen or oxygen and noticing an electrical voltage between the wires. A year later he published these results.

Next, he performed experiments on the electrolysis of water. He noticed a distinctive odor in his lab, which gave the scientist a clue to the presence of a new product from his experiments. Because of the distinctive smell, Schönbein coined the term ozone for the new gas, originating from the Greek word ozein – to smell. Schönbein’s discoveries were published in 1840. Later on, the scientist found that this particular smell of ozone was similar to that produced by the slow oxidation of white phosphorus.

Sometimes, Christian Friedrich Schönbein secretly experimented in his homes’ kitchen – even though his wife told him not to. In 1845 (when his wife was not at home), Schönbein spilled a mixture of nitric acid and sulfuric acid. The scientist used his wife’s cotton apron to mop it up, and he hung the apron over the stove to dry. However, the cloth spontaneously ignited and burned so quickly that it seemed to disappear. Schönbein had converted the cellulose of the apron, with the nitro groups serving as an internal source of oxygen. When heated, the cellulose was completely and suddenly oxidized.

Schönbein soon realized the possibilities of his new discoveries. In contrast to ordinary black powder, which exploded into thick smoke, nitrocellulose was perceived as a possible smokeless powder and a propellant for artillery shells thus it received the name of guncotton.

At first, it was nearly impossible to manufacture  guncotton for military use, because the factories were prone to explode and, above all else, the burning speed of straight guncotton was always too high. In 1884, Paul Vieille tamed guncotton into a successful progressive smokeless gunpowder called Poudre B. Seven years later, James Dewar [6] and Frederick Augustus Abel [7] transformed gelatinized guncotton into a safe mixture, called cordite because it could be extruded into long thin cords before being dried.

Schönbein’s research areas were far-reaching: in 1838 he coined the term geochemistry, developed the first test for the detection of blood from hydrogen peroxide in 1863 and dealt with biological questions, for example red blood cells, urine and fungi. He was particularly interested in the preservation of foodstuffs (meat, vegetables) against biological spoilage. Schönbein also dealt with the nitrogen-containing combustion products of the air and assumed that the inert atmospheric nitrogen is converted into ammonia-containing products in the plant by such oxidation processes. Schönbein now investigated the effect of nitrates and nitrites on plants.

In 1868 Schönbein took a cure in Bad Wildbad for gout. During a stay in Baden-Baden he died on August 29, 1868, at age 68.

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