Elements phlogiston theory

Stahl subsequently renamed the terra pingnis phlogiston, the motion of fire (or heat), the essential element of all combnstible materials. Thns the phlogiston theory was born to explain all combnstion and was widely accepted for most of the eighteenth centnry by, among others, such luminaries of chemistry as Joseph Priestley. 

In the days of alchemy and the phlogiston theory, no system of nomenclature that would be considered logical ia the 1990s was possible. Names were not based on composition, but on historical association, eg, Glauber s salt for sodium sulfate decahydrate and Epsom salt for magnesium sulfate physical characteristics, eg, spirit of wiae for ethanol, oil of vitriol for sulfuric acid, butter of antimony for antimony trichloride, Hver of sulfur for potassium sulfide, and cream of tartar for potassium hydrogen tartrate or physiological behavior, eg, caustic soda for sodium hydroxide. Some of these common or trivial names persist, especially ia the nonchemical Hterature. Such names were a necessity at the time they were iatroduced because the concept of molecular stmcture had not been developed, and even elemental composition was incomplete or iadeterminate for many substances. 

A. L. Lavoisier recognized oxygen as an element, developed the modem theory of combustion, and demolished the phlogiston theory. 

These genealogies, of course, take their point of origin not in ordinary people but in heroic figures who fought enemies, even villains, and who won their battles by wit and dexterity. Lavoisier s triumph over the evil forces of Georg Stahl and phlogiston theory is well known, and unlike most heroic scientists, Lavoisier met a martyr s end in the epic events of the French Revolution. This is historical mythology, a crucial constitutive element of the discipline. 3 5... 

The scientific revolution that began when Lavoisier announced his new theory of combustion was far from over. Chemists stuck to the phlogiston theory and some of them continued to cling to the old four-element theory as well, objecting that Lavoisier hadn t really shown that water could be decomposed. The hydrogen, they said, could have come from the hot iron over which the steam had been passed. 

This was the death blow to the phlogiston theory (56). Although Lavoisier discovered no elements himself, he was the first to assert that... 

Lavoisier summarized his ideas developed over the previous twenty years in his seminal 1789 book Traite Elementaire de Chimie (Elements of Chemistry). This work presented his findings on gases and the role of heat in chemical reactions. He explained his oxygen theory and how this theory was superior to phlogiston theory. Lavoisier established the concept of a chemical element as a substance that could not be broken down by chemical means or made from other chemicals. Lavoisier also presented a table of thirty-three elements. The thirty-three elements mistakenly included light and caloric (heat). Lavoisier put forth the modern concept of a chemical reaction, the importance of quantitative measurement, and the principle of conservation of mass. The final part of Lavoisier s book presented chemical methods, a sort of cookbook for performing experiments. 

Lavoisier s Elements of Chemistry synthesized and explained in a coherent manner the chemistry of his day. The work was readily accepted by many as a substantial improvement over the phlogiston theory. Young chemists quickly adopted Lavoisier s ideas and new nomenclature rather than trying to fit their work within a phlogiston framework. Upon reading Lavoisier s book,... 

Lavoisier, in his Reflections on Phlogiston published in 1786, points out that in Baum s view of the phlogiston theory, the combination of free fire and the earthy element can be combined in an infinity of proportions, and that there exists in consequence an infinity of intermediate states between the free fire and the phlogiston properly speaking. Lavoisier clearly recognizes the error of this view of continuous chemical combination, but he does not elaborate or generalize on this point. In his Traiti of 1789, he focuses chiefly on the empirically based distinction of the neutral salts, whose composition is expressed in terms of the operationally defined simple bodies. But in general he avoids the philosophical analysis. 

This definition was as accurate a definition as the knowledge of the time permitted and was indeed the same as given by Lavoisier and by later chemists until the development of the phenomena of radioactivity afforded a more intimate concept of the nature of the element. Neither Boyle nor his contemporaries ventured to assert that any known substance was such an element, and the subsequent rise and acceptance of the Phlogiston Theory tended to postpone any recognition of the elementary character of even such metals as gold or silver, until that theory was abandoned. 

Lavoisier formulated the rule that chemical reactions do not alter total mass after finding that reactions in a closed container do not change weight. This disproved the phlogiston theory, and he named Priestley s substance oxygen. He demonstrated that air and water were not elements. He defined an element as a substance that could not be broken down further. He published the first modern chemistry textbook. Elementary Treatise of Chemistry. Lavoisier was executed in the Reign of Terror at the height of the French Revolution. 

---