Abstract

In the middle of the 19th century the first chemical laboratories were established at hospitals and clinics in Central Europe which performed chemical analyses for purposes of practical medicine and clinical research. A characteristic feature of these new laboratories was the use of measuring instruments. The results of these chemical methods could serve as “signs” in the diagnosis of diseases. A great step forward was the introduction of “quantitative” data as results of measurements. They allowed a greater differentiation in the description of phenomena compared with the “qualitative” data used before. Another important feature of the new signs is the possibility to derive from it knowledge of causal relations of physiological and pathological processes in the organism. The influence of this methodological change on the thinking of the physicians at the sickbed is discussed using several examples. The “chemical signs” were used in the description of diseases and for the “quantification of health” by use of “normal values” which allow a discrimination between health and disease. Chemical quantities became also important for the description and examination of functional systems in the body, e.g. the metabolism