Alfred Stock was an experimentalist who made significant contributions to chemistry and designed several important chemical instruments. He worked on the creation of new boron and silicon compounds and the development of the chemical high-vacuum apparatus , which allowed him to work with volatile materials. The latter part of his life was particularly devoted to the study of mercury and mercury poisoning and, in particular, developing precautionary guidelines for other scientists to follow in order to avoid suffering from it. Stock contracted mercury poisoning while working with the substance in laboratories since his time in school; he was afflicted with the disease the rest of his life.
Stock was born in Danzig, West Prussia (now Gdansk, Poland) on July 16, 1876. His father was a banking executive. As a schoolboy, Stock developed an early interest in science, and he earned scholarships that allowed him to pursue a degree in chemistry at the University of Berlin in 1894. He chose to work at the chemical institute at the university, directed by Emil Fischer, but had to wait a year for space in the lab, which was overcrowded. He finally began his doctoral research in 1895 under the auspices of organic chemist Oscar Piloty. During his summer breaks from school, Stock worked in the private laboratory of the Dutch physical chemist Jacobus van't Hoff . It was there that Stock performed his first significant research in the areas of magnesium and oceanic salt deposits. After graduating magna cum laude in 1899, he spent a year in Paris assisting the chemist Henri Moissan at the Ecole superieure de Pharmacie, with support of the Prussian Ministry of Culture. At Moissan's lab he first investigated compounds of silicon and boron, which were to occupy him throughout his career.
Stock began his professional career in 1900 by working for nine years as a lab assistant with Fischer at the University of Berlin. There he investigated the preparation and characterization of such elements as phosphorus, arsenic, and antimony (a brittle, white metallic element). One result of Stock's investigation was that he could clearly explain their reactions with hydrogen, sulfur and nitrogen. He also identified an unstable yellow form of antimony, and two new compounds of phosphorus: a polymeric hydride, which is a compound including hydrogen and another element or group, and a nitride , which is a compound including nitrogen and one other element. Stock's research clarified misconceptions in scientific literature and established the existence of three of today's four well-established phosphorus sulfides, which are organic compounds of phosphorous and sulfur.
Unfortunately, it was also during these early years in Berlin that symptoms associated with Stock's mercury poisoning would begin surfacing. Headaches, dizziness and upper respiratory infections started plaguing Stock while he was pioneering his work with a device known as the vapor-tension thermometer. His success with the apparatus became well known throughout Germany and he later developed it into his tension-thermometer. Many years later, the work with the tension-thermometer was traced as the first of many sources of mercury poisoning to which Stock was exposed during the course of his life.
In July 1909, Stock was named full professor and director of the new Inorganic Chemistry Institute at Breslau. It was here that he surpassed previous chemists' successes with his imaginative work with hydrocarbons, inorganic carbon compounds and the development of a high-vacuum apparatus that allowed Stock to work with volatile and gaseous materials. The apparatus was later referred to as the Stock high-vacuum pump. He also envisioned at this time the possibility of developing the equivalent of organic chemistry's carbon-based system around boron, an element whose unanticipated potential he was just beginning to discover. His work with borohydrides, however, was interrupted with the outbreak of World War I. Stock was then charged with studying carbon subsulfide , an irritant, to determine its effectiveness as a war gas. The gas was never used, however, due to problems with polymerization, which is a chemical reaction in which molecules combine to form larger molecules that contain repeating structural units.
Stock left Breslau in April 1916 to continue his research and take charge of Richard Willstätter 's laboratory at the Kaiser Wilhelm Institute near Berlin. It was not long, however, before the military moved in and took over the institute. Since his still undiagnosed physical problems (including, by that time, an acute loss of hearing) kept him from serving in the military, he and his staff moved their equipment to the University of Berlin so that they could continue their work. When the war ended, he returned to the Kaiser Wilhelm Institute and continued to study silicon and boron hydrides. His work yielded a number of halogen and alkyl derivatives which, in turn, led to the discovery of new compounds such as silyl amines and silicones. In the process, Stock developed a chemistry based on silicon; this was similar to his work with boron at Breslau. At the suggestion of Hans Goldschmidt , Stock also collaborated on the production of metallic beryllium. This substance had become a worthwhile element to pursue because it is a metal which had possible applications in industry, so a beryllium study group was formed. By 1940, their new technique for making the material yielded enough beryllium to significantly reduce the market value per kilogram, thus increasing the element's cost-effectiveness in scientific experiments.
Stock's unexplained medical problems kept growing worse. Besides headaches, vertigo, respiratory infections, and deafness, he now also suffered frequent numbness. None of these symptoms was alleviated by medical treatment. In 1923, he suffered virtually total hearing and memory loss, and he almost didn't make it through the winter of 1924. At that time, many scientists in addition to Stock were unknowingly being exposed to mercury poisoning . It wasn't until after he saw similar symptoms in a colleague that Stock finally realized the volatility of this odorless substance. He began researching mercury poisoning, often experimenting on himself. As a result of his investigations, Stock published several articles outlining the dangers of mercury and offered up numerous precautionary guidelines for working with the substance.
It was a difficult decision, but the opportunity to establish a new mercury-free laboratory convinced Stock to leave the Kaiser Wilhelm Institute in 1926 to become the director of the Chemical Institute at Karlsruhe. The next ten years of his life were devoted exclusively to the study of mercury poisoning and borohydrides. His concepts and working models of laboratory rooms equipped with extensive safety precautions were sought after by scientists from around the world. Further experiments proved that inhaled mercury vapor was much more dangerous than ingested mercury because the vapor, entering through the nose, moved more quickly into the pituitary gland, where it wreaked havoc on the body. Stock also pioneered a teaching method during his tenure at Karlsruhe which used reflected light to project chemical objects on a large screen. Stock worked with his lecture assistant, Hans Ramser, and with Carl Zeiss-Jena to create this apparatus, which was called an epidiascope.
Stock married Clara Venzky in August of 1906 and later had two daughters. He was the president of the Verein Deutscher Chemiker (Association of German Chemists) in Paris in 1927 and later the Deutsche Chemische Gesellschaft (German Chemical Society) from 1936 to 1938. He was a guest professor at Cornell University for several months in 1932 under the George Fisher Baker Nonresident Lectureship in Chemistry. The last ten years of Stock's life were nearly unbearable, both physically and professionally. His mercury poisoning became debilitating and interfered with his work. His political differences with the Nazi government were increasing. In 1936, at the age of 60, he asked for his retirement. He returned with his family to Berlin where he continued to trace and validate the chemical path of mercury poisoning. By 1940, movement became difficult as he developed hardening of the muscles. Stock relinquished his laboratories in 1943 because they were needed for the war effort, and he and his wife moved to Bad Warmbrunn in Silesia to live with his brother-in-law. As the Russians were approaching in 1945, Stock and his wife again moved and sought shelter with an old friend, Ernst Kuss, in Dessau. The Stocks finally found refuge in a barracks in Aken, a small city on the Elbe. Stock died in the early morning of August 12, 1946.
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