Illustration of Chlorine

1774,1810 Chlorine

The book of science

Tom Sharp

Carl Wilhelm Scheele, Humphry Davy elements Illustration of Chlorine


Carl Wilhelm Scheele was the first to isolate its gas but he thought it was oxidized hydrochloric acid, which he called “dephlogisticated muriatic acid.” Thirty-six years later, Humphry Davy showed it contained no oxygen, and was, in fact, a new element, which he called “chlorine.”

The meaning of oxygen

Scheele thought his “dephlogisticated muriatic acid” was dephlogisticated because it acted as an acid. Antoine Lavoisier had taught that acids had to be dephlogisticated, that is, that oxygen was the principle that made things acidic.

Pale green

Sodium chlorine, common salt, as necessary for human life as water. Chlorine or chloramine as a disinfectant in our water supplies at four parts per million, ideally, except as a shock treatment at forty, in swimming pools at three, typically, not to exceed ten, legally, killing algae, bacteria, viruses, and creatures in aquariums. reacting with urine to produce volatile toxins damaging lungs, hearts, and central nervous systems although water without a disinfectant damages more, killing people. Extremely toxic to all living things, elemental chlorine gas was the first chemical weapon causing coughing and vomiting at thirty parts per million and lung damage at sixty parts per million.


I don’t think I like it, or the thought of it, in this escalating war of invisible agents both friends and foes offend. Our defenses are inadequate. Too much, too many, too often, too close, too far, too weak, too strong, too soon, too late, and too unfair.

For an explanation, too contravoluted to repeat here, of why “dephlogisticated” meant oxygenated, look up phlogiston theory or see “Combustion.” It took a long time for chemistry to disengage from alchemy, but Lavoisier was one of the first to do it.

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