Abstract
SUMMARY: The investigation of Didericus de Smeth on the fixed air (1772). In his well-known February Memorandum — a sketch to future research on combustion — Lavoisier refers to the thesis of Didericus de Smeth (1754-1779), « De Aere Fixo» (9 October 1772). Didericus or Dirk de Smeth studied with
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his brother Petrus (1753-1810) at the University of Utrecht. They belonged to a well-known Amsterdam family of patricians. Little is known about Dirk: he already died on the age of twenty-five. The brothers de Smeth were pupils of Johannes David Hahn (1729-1784), from 1753 professor in philosophy, experimental physics, and astronomy, and from 1759 in medicine, botany and chemistry at the University of Utrecht. Hahn's special interest was in the experimental study of the natural sciences. As his teacher Petrus van Musschenbroek, he emphasized on observation and on experimentation. Under his direct guidance a number of dissertations on experimental chemistry and physics were prepared. Dirk de Smeth's thesis deals with a quantitative study of the increase of weight of phosphorus and of quicklime both on exposure to air. De Smeth and Hahn concluded that the increase of weight of quicklime is due mostly to the absorption of moisture and only to a very minor part of air. With a Hungarian student of Hahn, Michael Paxi de Szathmar (1771), they believed that also the increase of weight of phosphorus to the air must be ascribed to the absorption of water.From the thesis it follows clearly that de Smeth and Hahn had no insight into the essential difference between the atmospheric air and the fixed air. From their experiments they concluded that the property of a substance to effervesce with acids do not depend on an avoiding, but on an adding substance. The doctrine of Joseph Black on fixed air was rejected : it is based on problematic and weak grounds. The theory of the Utrecht chemists was an intermediate from between that of Black and the « acidum pingue » doctrine of Johann Friedrich Meyer (1764). Hahn and de Smeth were not the only Netherlanders who had serious objections to the concepts of Black. The Amsterdam apothecary Petrus Johannes Kasteleyn translated Meyer's book (1776-1777) and was an adherent of the «acidum pingue». Only a few years later (1786) he declared himself to be a Blackian. The professor of chemistry at Leyden, David Hieronymus Gaubius, was very sceptical against the experiments of Black (1781), as were the Amsterdam chemists Jan Rudolph Deiman and Adriaan Pacts van Troostwijk, as well as the Groningen apothecary Boudewijn Tieboel. The discussion ended with the adoption of the antiphlogistic system of Lavoisier in the Netherlands from 1787 onwards.
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