| Whereas a large proportion of chemical reactions | | | | chemistry, by being the devil's advocate against the |
| involve changes in oxidation states, one of the most | | | | Antiphlogistians, and by discovering important |
| vehement disputes, in the history of chemistry, | | | | experiments. And, for almost the entire 18th century, |
| concerns the nature of oxidation. In 1718, George | | | | the phlogiston theory was more satisfying than the |
| Stahl, a German Chemist, proposed that metals form | | | | alternative, in some ways. The Antiphlogistians |
| from oxides that are heated with charcoal because | | | | deduced that combustion was combination of a |
| the metals absorb a substance that he named | | | | substance with oxygen (Priestley's dephlogisticated |
| Phlogiston. He also proposed that the heating of a | | | | air). But, they could not tell why substances combined |
| metal in air to form its oxide caused the release of | | | | with oxygen, or even why all substances didn't just |
| phlogiston to the atmosphere. | | | | burn up. Phlogiston theory explained this by saying |
| Phlogiston theory evolved throughout the 18th | | | | that it was because some substances were rich in |
| century, because many experiments were being | | | | phlogiston, and burned. It was only later that more |
| performed which needed to be explained. Though | | | | satisfactory explanations were discovered. |
| phlogiston theory made some sense, the | | | | It may seem hard to believe that phlogiston theory, |
| experiments which, more and more, convinced | | | | which is incorrect, was so persistent. How could it |
| chemists that phlogiston was incorrect, were | | | | survive all of the attacks, and come back for more? |
| quantitative experiments. Most of these experiments | | | | People think that the answer is that phlogiston |
| were being performed by Antoine Lavoisier who is | | | | theory is actually very close to the truth. If we |
| called as the father of modern chemistry and his | | | | consider a chemical's tendency to take up oxygen, |
| followers, known as the Antiphlogistians. They would | | | | and call its lack of oxygen "phlogiston," we can |
| come up with an objection to phlogiston theory, and | | | | describe absolutely any chemical reaction involving |
| the Phlogistians (usually Priestley) would modify the | | | | oxygen. Instead of putting oxygen on one side of |
| theory to fit the new experiment. As the years went | | | | any chemical equation, we can put this anti-oxygen |
| on, more and more Phlogistians became | | | | on the other side. It will always balance. One atom of |
| Antiphlogistians, until only Priestley was left. The | | | | phlogiston would always have an atomic weight of |
| Antiphlogistians measured the weight of every | | | | -16, and the weights will always balance, too. So, we |
| substance involved in the experiment, even the | | | | can always construct a self-consistent phlogiston |
| gasses. When iron rusts away completely, the rust | | | | theory, even today. We can go about disproving the |
| actually weighs more than the original iron. When | | | | theory of phlogiston if we merely burn carbon in |
| charcoal burns, the resultant carbon dioxide (fixed air) | | | | oxygen, and accurately measure all of the gasses |
| weighs more than the original charcoal. So, in every | | | | and solids, before and after. We would find that |
| case, phlogiston would have to have a negative | | | | carbon plus oxygen became carbon dioxide. We can |
| weight. This disturbing attribute convinced most of | | | | determine that the final gas contains carbon dioxide. |
| the last Phlogistians to abandon their theory. | | | | If we start with the right amounts of carbon and |
| Fifty four years later, the French chemist | | | | oxygen, we may be able to show that the final gas |
| Louis-Bernard Guyton de Moravia stated that | | | | is nothing but carbon dioxide. |
| phlogiston has a negative weight in order to explain | | | | It is worth mentioning that taking it for granted that |
| his findings that during combustion metals increase in | | | | the editors of the French Science Journal would not |
| weight. Soon after, it was Antoine Lavoisier who | | | | publish his proposal due to his phlogiston Inclination, |
| dared to question the phlogiston concept and | | | | Lavoisier, with his new converts and associates, had |
| proposed that combustion was due to addition of | | | | to establish a new journal to publish his new |
| oxygen to the metal (oxidation) and that the | | | | Chemistry. Fortunately, it was the overthrow of the |
| formation of a metal from an oxide corresponded to | | | | phlogiston theory that caused chemists to realize that |
| the loss of oxygen (reduction). The Phlogistians were | | | | elements were the fundamental substances in |
| not a bunch of cranks. They were serious scientists | | | | chemistry and the modern chemistry came into being. |
| who helped resolve some of the basic questions of | | | | |