Sunday, June 23, 2013

Johannes Wislicenus

Johannes Winlicenus was born on June 24, 1835 in Kleineichsted, Saxony, the son of Gustav and Emilie Winlicenus. He was born into a devout protestant family that in the 17th century had been forced to flee their native Poland to Saxony on account of their religion. His father was a protestant minister who in 1853 published a book in which he attempted to liberate people from what he thought was a "superstitious adoration" of the Bible. The book was considered blasphemous by the authorities, and so it was destroyed and he was sentenced to two years in prison. Instead he fled with his family to Boston, Massachusetts. Johannes who was 18 at the time served as an assistant to chemist Eben Horsford at Harvard University and in 1855 he as appointed lecturer at New York's Mechanic's Institute. Returning to Europe in 1856 he went to the University of Halle where he resumed his studies and served as an assistant to Wilhelm Heintz. He had finished the requirements for his PhD by 1859 but as a condition of his graduation he was asked to renounce the teachings of his father and cease his political activities. He refused and then went to the University of Zurich where he finished his doctorate in 1860. He served as a lecturer at the University of Zurich until 1868 when he became a professor of chemistry there. In 1860 he became professor of chemistry at the Swiss Pyrotechnical Institute and he served both professorships simultaneously. In 1872 he became the chair of chemistry at the University of Wurzburg and in 1885 he became a professor of chemistry at the University of Leipzig.

Winlicenus' research was in organic chemistry. Starting in 1868 he began studying lactic acid. Lactic acid is a  carboxylic acid that is a metabolite of glucose. In his studies he found that there were two types of lactic acid which had different chemical properties. While these two chemicals have the same chemical formula (the same numbers and types of atoms) they have different structures. In the case of lactic acid (a three carbon long carboxylic acid) one form has a hydroxyl group attached to the carbon adjacent to the carbonyl carbon and the other form has a hydroxyl group attached to the terminal carbon, the carbon on the opposite end of the three carbon chain from the carbonyl. Because these two molecules have different structures they have different properties, but the formulas for both compounds are both C3H6O3. Winlicenus called these chemicals with the same formula but different structures structural isomers.

Another important experiment carried out by Winlicenus, working in collaboration with his friend Aldolf Fick a professor of physiology at the University of Zurich, showed that carbohydrates and fats were the principal source of muscular energy. The pair ascended the Faulhorn, taking with them only food from which proteins had been excluded. While they climbed the pair monitored their nitrogen metabolism and found that the the break down of proteins accounted for less than one third of the energy generated by their metabolism.

Wislicenus was elected a foreign member of the British Royal Chemical Society in 1888 and member of the Royal Society of London in 1897 which presented him with its Davy Medal in the following year.

Winlicenus died on December 5, 1902.


P.F.F.; "Johannes Wislicenus. 1835-1902"; Proceedings of the Royal Society (1907) 78:iii-xii

Ramberg, Peter J.; Chemical Structure, Spatial Arrangement: An Early History of Stereochemistry. 1874-1914; Ashgate Publishing Ltd.; 2003

"Johannes Wislicenus, Biography", retrieved from:

Johannes Wislicenus Wikipedia Entry

Sunday, June 9, 2013

Giovanni Cassini

Giovanni Domenico Cassini was born in Perinaldo in northern Italy on June 8, 1625. He was brought up by his maternal uncle who looked after his education. He attended school in Valebone for two years and then attended the Jesuit college in Genoa where he studied astrology and astronomy. Although he studied astrology he admitted that it was not prophetic but at the time there was little separation between astronomy and astrology. In 1644 he was invited to become an assistant at the Bologna Observatory and six years later, when he was still only 25, he was made professor of astronomy and mathematics at the University of Bologna. In addition to his astronomical work, Cassini also did river engineering work and engineered fortifications for the Holy See. In 1668 he was invited to help set up the new Paris Observatory by Louis XIV of France. Pope Clement IX agreed to the trip believing it would be short, only two years at the most. Cassini once established in the new observatory made no effort to return to Italy. He remained at the Paris Observatory and three generations of his descendants ran it until 1794.

Cassini is probably best remembered for discovering the Cassini Division, a open space between Saturn's A and B rings. Before Cassini it was believed that the rings of Saturn were one large solid ring structure orbiting the planet. Cassini's observations of the rings showed that there were breaks between the rings. We know now that the rings of Saturn are not solid at all, but made up of orbiting pieces of ice and debris. Cassini was also responsible for identifying four of the moons orbiting Saturn: Iapetus, Rhea, Tethys, and Dione. Cassini also shares credit for discovering the red spot on Jupiter with English scientist Robert Hooke Although Cassini initially believed in a geocentric model for the solar system he eventually came to believe in a solarcentric model, similar to that proposed by Nicolas Copernicus.

In addition to craters on the moon and Mars named after him Cassini also has an asteroid named after him. Additionally NASA's unmanned probe that is currently exploring Saturn and its moons is named after him (for more information on the Cassini probe see here).

As he grew older Cassini's vision failed him and his son Jacques began to run the Paris Observatory. Cassini died on December 14, 1712.


Connor, Elizabeth; "The Cassini Family and the Paris Observatory"; Astronomical Society of the Pacific Leaflets (1947)218:146-153

O'Connor, J.J. and Robertson, E.F.; "Giovanni Domenico Cassini"; Retrieved from:

Giovanni Domenicao Cassini Wikipedia Entry

Sunday, June 2, 2013

Otto Loewi

Otto Loewi was born in Frankfurt, Germany on June 3, 1873. His father Jacob was a Jewish wine merchant. He attended gymnasium school in Frankfrurt and then the Universities of Munich and Strasbourg as a medical student. Not really interested in clinical medicine, Loewi applied himself to physiology and pharmacology. He completed his thesis on the effects of arsenic, phosphorus, and other substances on an isolated frog heart. After completing his medical education in 1896, Loewi spent a year as an assistant doctor in a hospital in Frankfurt. There he was frustrated by the lack of effective treatment for tuberculosis and pneumonia patients. This convinced him that he did not want to practice clinical medicine and opted instead for a research career. He was able to get a position as an assistant to Hans Meyer starting work in Meyer's laboratory in Marburg in 1898. Working in Meyer's lab he researched metabolism. While working there he proved that animals were able to synthesize proteins from protein degradation products (amino acids). Before that it was believed that animals could only make proteins from other intact proteins.

In 1903 he was appointed professor of pharmacology at the University of Graz in Austria. While working at Graz he conducted an experiment that proved that the transmission of nerve impulses to the heart was conducted by a soluble factor, the idea for which came to him in a dream. First he isolated two frog hearts, one with the vagus nerve still attached. The vagus nerve is part of the parasympathetic nervous system and causes the heart muscle to slow its beating. First he stimulated the attached vagus nerve, which caused the attached heart to slow its beating. Taking a sample of the fluid surrounding the heart with the attached nerve he applied it to the second heart. The second heart slowed its beating in response to the added fluid. Loewi named the unknown soluble factor that caused the second heart to slow its beating "vagustoff". It was later identified as acetylcholine. The transmission of nerve impulses between different neurons and at the nerve interfaces with muscles are conducted by soluble chemicals called neurotransmitters. For his pioneering work establishing the importance of neurotransmitters Loewi shared the 1936 Nobel Prize in medicine and physiology with Henry Dale. He would remain in Austria until 1938 when he was forced to leave due to the German occupation. After a brief stays in Belgium and the United Kingdom, Loewi emigrated to the United States in 1940

Other honors won by Loewi include honorary doctorates from the University of Graz, Yale University, University of New York (where he worked after he emigrated to the United States) and the University of Frankfurt. He was made an honorary member of the Physiological Society of London and a member of the Royal Society.

Loewi died on December 25, 1961.


Valenstein, Elliot S.; The War of Soups and the Sparks: The Discovery of Neurotransmitters and the Dispute Over How Nerves Communicate; Columbia University Press; 2005

Otto Loewi Nobel Biography

Ottto Loewi Wikipedia Entry