Pneumatic chemistry
In the history of science, pneumatic chemistry is an area of scientific research of the seventeenth, eighteenth, and early nineteenth centuries.
Important goals of this work were the understanding of the physical properties of gases and how they relate to chemical reactions and, ultimately, the composition of matter.
[1] This study of gases was brought about by Hales with the invention of the pneumatic trough, an instrument capable of collecting the gas given off by reactions with reproducible results.
This term was derived from the Ancient Greek word χάος, chaos, as a result of his inability to collect properly the substances given off by reactions, as he was the first natural philosopher to make an attempt at carefully studying the third type of matter.
[2] Van Helmont (1579 – 1644) is sometimes considered the founder of pneumatic chemistry, as he was the first natural philosopher to take an interest in air as a reagent.
[3] Alessandro Volta began investigating pneumatic chemistry in 1776 and argued that there were different types of inflammable air based on experiments on marsh gases.
Other individuals who investigated gases during this period include Robert Boyle, Stephen Hales, William Brownrigg, Antoine Lavoisier, Joseph Louis Gay-Lussac, and John Dalton.
During the eighteenth century, many chymists used the discovery of airs as a new path for exploring old problems, with one example being the field of medicinal chemistry.
[2] Gaseous ammonia was first isolated by Joseph Black in 1756 by reacting sal ammoniac (ammonium chloride) with calcined magnesia (magnesium oxide).
[19] Boerhaave is also credited with adding to the world of chemical thermometry through his work with Daniel Fahrenheit, also discussed in Elementa Chimiae.
After the invention of the pneumatic trough, Stephen Hales continued his research into the different airs, and performed many Newtonian analyses of the various properties of them.
He published his book Vegetable Staticks in 1727, which had a profound impact on the field of pneumatic chemistry, as many researchers cited this in their academic papers.
While this was the major adaptation of the trough in the eighteenth century, several minor changes were made before and after this substitution of mercury for water, such as adding a shelf to rest the head on while gas collection occurred.
[2] A practical application of a pneumatic trough was the eudiometer, which was used by Jan Ingenhousz to show that plants produced dephlogisticated air when exposed to sunlight, a process now called photosynthesis.
