Thomsen, Hans Peter Jorgen Julius

His most famous achievement was the discovery of the -> endothermic galvanic cells in 1897 [i,ii]. It was the first evidence that endothermic reactions can proceed spontaneously. Therefore, it supplied a verification of the concept of -> Gibbs and -> Helmholtz regarding the nature of affinity, i.e., the Gibbs free energy of reaction is of importance and not the heat of reaction (enthalpy) as claimed by Pierre Eugene Marcellin Berthe-lot (1827-1907) and Hans Peter Jorgen Julius Thomsen (1826-1909). 

Using such a calorimeter (from the Latin for heat-measure), Berthelot ran careful determinations of the quantity of heat evolved by hundreds of different chemical reactions. Independently, the Danish chemist Hans Peter Jorgen Julius Thomsen (1826-1909) did similar experiments. 

In this essay I examine how the periodic system or table was introduced in Denmark in the late nineteenth century, how it was used in chemical textbooks, and the way it was developed by a few of the country s scientists. Danish chemists had in the period an international orientation, which helped them in getting acquainted with Mendeleev s system and appreciating its strength. The main reason they felt the system to be attractive was its predictive force, especially its prediction of new elements and ability to accommodate new chemical knowledge. I pay particular attention to the work of Hans Peter Jorgen Julius Thomsen (1826-1909), which is an important example of neo-Proutean attempts to understand the periodic system in terms of internally structured atoms. Moreover, I direct attention to Mendeleev s connection to Danish science by way of his membership in the Royal Danish Academy of Sciences and Letters. 

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See also in sourсe #XX -- [ ]

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