Technoscience in History by Ursula Klein

Author:Ursula Klein
Language: eng
Format: epub
Publisher: The MIT Press

Shortly afterward, Humboldt published technical details of his inventions in the Annalen der Chemie.37

Parallel to his work of invention, Humboldt began to perform chemical analyses of gases. In mid-September 1796 he wrote to Freiesleben that he was experimenting in mines with pure gases and mine airs.38 These experiments served two goals. First, Humboldt wanted to expand his subterranean meteorology to include knowledge about subterranean combustion and about the chemical composition of different kinds of mine air. Second, knowledge about the composition of mine airs was crucial for testing the functionality of his lamp. During his tests of the lamp in the alum mine, mentioned in the letter quoted above, the lamp extinguished repeatedly. This could have been for two different reasons: either the experimenter’s mechanical handling of the lamp was wrong, or the oxygen content of the mine air was extremely low and the lamp’s air supply needed to be improved. The analysis of the mine air with a eudiometer proved that the latter was the case. Hence, Humboldt also reported to Freiesleben about his idea for “how more air can be transported to the flame” of the lamp.39 A new device was needed that delivered more air to the flame without extinguishing it simultaneously. The solution to the problem consisted of the construction of an annular tube with numerous small openings, which replaced the simple opening of the main tube connected with the air container of the lamp.

The chemical analysis of different kinds of “air” or “gases” was a flourishing field in late eighteenth-century chemistry that had been established only in the middle of the century and comprised both conceptual and technical innovations. “Air” had long been considered as a simple element, and chemists had thus assumed that there was one kind of elemental air. The new field of “pneumatic chemistry” also brought a plethora of new instruments and techniques into the chemical laboratory. It required familiarity with the experimental methods of preparing and purifying different kinds of air (gases), and technical know-how about the construction and manipulation of related instruments and apparatus. Furthermore, the analysis of gases involved chemical knowledge about the interaction between gases and reagents, qualitative methods for the identification of different kinds of gases, and quantitative methods for the determination of the proportions of the different components in a gaseous compound or in a mixture of different gases. The most important instrument allowing the latter was the eudiometer.

The English chemist Joseph Priestley had introduced the eudiometer to measure the “vital air” (oxygen) contained in common air. In September and October 1796 Humboldt tested different types of eudiometers and built replicas of the eudiometers by Heinrich Reboul and Guyton de Morveau, which used solid reagents for binding oxygen. De Morveau’s eudiometer, he reported to Freiesleben, “is easy to make oneself and magnificent for investigating mine air!” Shortly afterward, he wrote, “I am going down [into the mines] diligently and now am really conducting experiments about the analysis of the weather [mine airs], which are quite striking. For I have simplified Reboul’s phosphorus eudiometer such that I can make the instrument myself.

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