Alan Aitken of the University of St Andrews in Scotland discovered a roll with the periodic table of Mendeleev's chemical elements, which is estimated to be 133-140 years old. It is currently the oldest known table. This is reported by Science Alert.
A researcher found a poster, written in German, in a storage room under a chemistry lecture hall, among chemicals and laboratory equipment. It was analyzed by an expert from the University of California at Los Angeles and the age of the table was determined based on the chemical elements depicted on it. So, germanium, discovered in 1886, is not indicated, unlike gallium and scandium, discovered in 1875 and 1879, respectively.
In addition, it turned out that the Scottish University purchased the table from a publisher based in Vienna, Austria. Thus, the educational material was released less than twenty years after Dmitry Mendeleev discovered the periodic system of chemical elements.
The recovered poster has undergone restoration and conservation, including cleaning the paper and dipping in a chemical solution to maintain the correct acidity. The artifact will be stored at the University of St Andrews.