Pneumatic chemists

Following the practice of the pneumatic chemists (chemists who were studying the properties of gases or airs ), he trapped and characterized this new gas. Fixed air was found to be mildly acidic. It would later be called carbon dioxide, and stones that generated this gas would be defined as carbonates. Black also discovered that the chemical nature of the gas that had been produced in these experiments was determined by the stone it came from, not by the acid used. 

Cavendish, Henry (1731-1810) British chemist and physicist in London he is considered to be one of the so-called pneumatic chemists of the eighteenth and nineteenth centuries, along with, for example, Joseph Priestley, Joseph Black, and Daniel Rutherford by combining metals with strong acids, Cavendish made hydrogen (H2) gas, which he isolated and studied. 

But then antisocial behavior seems to have been common among pneumatic chemists, as evidenced by our next chemist, Henry Cavendish. Cavendish was the first to study hydrogen, the infamous gas of the Hindenberg dirigible explosion. Cavendish calmly calls it his inflammable air. 

For whatever reasons though, Cavendish was antisocial to the bitter end. On his deathbed he was attended only by his valet, and he even sent him away, asking not to be disturbed until a certain hour. When the valet returned at that hour, he found his employer dead. We begin to suspect that there was something in the air of these pneumatic chemists, because our next subject also seems to have had his own peculiar social habits. 

Black s work on alkalis had revealed some important properties of fixed air, and it was with this gas that the most famous of all pneumatic chemists, Joseph Priestley (1733-1804), commenced his researches around 1767. In that year he moved to the Mill-Hill chapel in Leeds, and by good fortune the chapel was close to a brewery, so he had an abundant supply of fixed air produced by fermentation. Priestley found that the gas would not support combustion and that mice soon died when placed in it, but that both the respirability of the gas and its ability to support combustion were improved by growing a plant in it. He also discovered that fixed air could be dissolved in water to produce what we would call carbonated or soda water. He recommended that brewers should manufacture soda water, and although he made no attempt to take any financial gain for himself, he became even more well known as a result of the invention. 

For most of the eighteenth century the phlogiston theory was the principal theory of chemistry. As chemical knowledge increased, the theory was forced to adopt ever more convoluted explanations to account for the new discoveries. The pneumatic chemists provided the evidence upon which a new theory could be based. The chemist who was principally responsible for sweeping aside the old ideas and bringing about a revolution in chemical thought was Antoine Laurent Lavoisier. 

Davy did not stay a pneumatic chemist very long. In 1800, just before the young Davy arrived in London, Alessandro Volta announced his construction of the first chemical battery (a voltaic pile ) capable of producing a sustained and predictable current. As soon as word of this battery came to Davy, he built one and—you guessed it—immediately tested it by administering a series of shocks on himself Immediately, Davy realized that his future lay in electrochemistry, not pneumatic chemistry. 

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