Regarded as one of the rarest elements on Earth, Osmium, with the symbol “Os” and atomic number 76 in the periodic table, is a hard and brittle metal that has a bluish-white color. This element belongs in the platinum group and is considered as the densest naturally occurring element with a calculated density of 22.59 g/cm3. Osmium has many applications in different industries despite its rarity, although the price of objects or devices with osmium can be quite high. To understand the reason why this element is highly sought-after, let us check out the interesting discovery of osmium.
Discovery of Osmium
Osmium was discovered by chemists William Hyde Wollaston and Smithson Tennant in 1803 in their lab somewhere in London, England. Around the same year, Wollaston was also able to discover two new elements, namely palladium and rhodium, in a crude platinum ore that he got from South America. Much like the two mentioned elements, the discovery of osmium is also linked to the utilization of platinum ores for research. The element known as platinum was first discovered by a group of miners during the 17th century in Colombia, and a few decades after that, Europe began getting platinum ores, which they call “platina” (“small silver” in English), as a material for various applications. However, even though platinum was encountered in the 17th century, it was not until 1748 when it was considered a new element.
For the discovery of osmium, the two chemists implemented the process that Wollaston conceptualized to bring palladium and rhodium out of the platinum ore, and that is to dissolve the material in aqua regia, a mixture of nitric and hydrochloric acids. When they performed the said process, they noticed that there is a dark and insoluble residue that comes out of the platinum ore. French chemist Joseph Louis Proust first thought that the dark residue was graphite, a crystalline form of carbon, another chemical element. The second group of chemists, which consists of Antoine Francois, Comte de Fourcroy, Victor Collet-Descotils, and Louis Nicolas Vauquelin, was also able to bring out the dark residue in 1803, but they were unable to produce a sufficient amount that will allow them to study it more. However, just a few months later, two of the chemists in the group, namely Fourcroy and Vauquelin, identified the metal found in the residue with a new name, “ptene.”
Going back to Wollaston and Tennant’s research, the latter was able to analyze the residue and stated that it contains a new metal element. In the research spearheaded by Vauquelin, they obtained a new oxide that was volatile and came from the new metal that they discovered. From there, the chemists named the new metal as “ptene,” the Greek word for “winged.” However, in the research conducted by Wollaston and Tennant, he obtained a yellow solution through the reaction of sodium hydroxide in intense heat. After the acidifying process that distills the solution, he found out that there are actually two elements found in the residue, and these elements are iridium and osmium. Tennant then named osmium after the Greek word “osme,” meaning “smell,” as it produced a smoky smell when he separated the element from the platinum ore. The research paper written by Tennant and Wollaston was then published as a letter to The Royal Society of London for Improving Natural Knowledge on June 21, 1804.
In the Haber process (the nitrogen fixation reaction of hydrogen and nitrogen that can produce ammonia), it was discovered that osmium and another element, called uranium, were regarded as successful catalysts, or elements that can increase the chemical reaction when mixing two or more elements. In order to conduct more studies on osmium, a group created by the BASF (Baden Aniline and Soda Factory) and led by German engineer Carl Bosch purchased almost all of the world’s supply of osmium in the early 1900s in order to utilize it as a catalyst. In 1908, cheaper catalysts that are derived from iron oxides were introduced, thus making osmium almost unusable for catalyst research because of its rarity and price.
Despite not being used as a catalyst anymore, osmium is still utilized in various applications. Osmium is commonly used to make the tips for expensive fountain pens, as it is quite resistant to wear and tear, and it glides on paper much smoother than any other material. Furthermore, osmium was also utilized to make a sturdy and durable stylus, which is the part of a phonograph that comes into contact with the vinyl record. The reason for applying osmium in phonographs is also the same in fountain pens, as they are strong and durable without being heavy enough to scratch the vinyl records. A compound of osmium, osmium tetroxide, is utilized for fingerprint detection, as it would stain the biological membranes in the tissues of the skin, thus allowing the fingerprint to be read clearer by the machine.