海尔曼·科普
Hermann Kopp (1817-1892): First historian of chemistry
HERMANN KOPP was born at Hannau, Germany. His father, though a practising physician had a strong interest in teaching science which he did in the local school.
Besides he maintained a large mineralogical collection. Young Kopp was thus exposed in his boyhood to chemistry and crystallography.
After his studies at the Hannau Gymnasium, Kopp enrolled at the University of Heidelberg for studying philology, to continue the subjects of his school days, Latin and Greek. This linguistic training was later of very great value to him in his work.
The lectures of Leopold Gmelin, professor of Chemistry, aroused his interest. He therefore decided to devote himself to chemistry. Due to lack of facilities for experimental work at Heidelberg, he went to Marburg.
Kopp received his doctorate degree in 1838. His thesis was concerned with the links between the physical and chemical properties of elements and compounds.
Kopp shifted to Geissen in 1839 to work with the greatest chemist of his time, Liebig (1803-1873), serving there for 24 years. He carried out most of his experimental work during this period. When Liebig left Giessen for Munich, Kopp and Heinrich Will were jointly appointed to succeed him. He maintained intimate relations with Liebig and corresponded with him for the rest of his life, often complaining in his letters about his poor health.
While at Geissen, he began to collect materials on the history of chemistry; he made this subject one of his main teaching activities.
In 1863, Kopp shifted to Heidelberg where he spent the rest of his career till he retired in 1890. He gave courses only in crystallography and the history of chemistry.
Measurement of physical constants
Kopp seldom worked with students and carried out most of his experiments by himself. Beginning with his first published paper (1837) on the construction of a differential barometer, he delighted in designing and building the apparatus needed for many accurate measurements of physical constants such as boiling point, specific heat and specific gravity.
Kopp determined the specific gravity of a number of different compounds.
For calculating such values, he used the concept of specific volume, which he defined as the molecular weight divided by the specific gravity of the substance.
He showed the similarity of this value in similar elements and the relation to their crystal structure. He also evolved (1841) the relations between chain length and boiling point in various classes of organic compounds.
In 1864 Kopp verified Neumann's Law that the product of molecular weight and specific heat of an element is a constant. He was able to show that each element has the same specific heat in its solid state as in its solid compounds.
Though Kopp's general theory often had to be modified later, the relation he presented between physical properties and chemical structure opened the way for advances in both organic and physical chemistry.