The Karlsruhe Congress and its Aftermath

As a result of this confusion, Kekule conceived the idea of calling an international meeting of chemists to consider the problems besetting their subject. In 1859 he discussed this proposal with his friend Carl Welzein (1813-1870), who was professor of chemistry at the Technische Hochschule in Karlsruhe. Welzein undertook to organise an International Chemical Congress in Karlsruhe the following year. Welzein s letter of invitation, sent to all the prominent chemists of Europe, commenced  

Chemistry has reached a state of development when to the undersigned it seems necessary that a meeting of a great number of chemists, active in the science, who are called upon to do research and teach, be held so that a unification of a few important points shall be approached.  

Cannizzaro spoke in favour of the barred symbols but his contribution was more important for its strong advocacy of Gerhardt s atomic weights. One of the delegates whom Cannizzaro influenced was Mendeleev, who later recalled  

As Mendeleev indicated, no agreement was reached at the meeting. However, Cannizzaro had taken the precaution of bringing along some reprints of a paper that he had published two years earlier. As the delegates left the conference, a friend of Cannizzaro s, Angelo Pavesi, distributed the pamphlets. Julius Lothar Meyer (1830-1895) later recorded the impression the paper made on him as he travelled home The scales fell from my eyes, doubts vanished and were replaced by a feeling of the most peaceful assurance . 

The year of the Karlsruhe Congress also saw the introduction of a technique which resulted in the detection of several new elements. The number of known elements had remained at 58 since 1844, since those as yet unknown were generally present in minerals in quantities too small to be revealed by the analytical techniques then in use. It was with the introduction of the spectroscope by Bunsen and Gustav Robert Kirchhoff (1824-1887) in 1860 that the detection of further elements became possible. 

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