A non-technical historically-based introduction to chemistry based on the periodic table. Well done.
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The author occasionally uses casual modern English. It is unnecessary and distracting.

The author states that the association of iodine deficiency with mental retardation made Bertrand Russell realize that mental function depends on the material conditions of the brain. I don't believe it. After all, Heraclitus of Ephesus said, A blow to the head will confuse a man's thinking; a blow to the foot has no such effect. This cannot be the result of an immaterial soul., and Russell wrote a great history of philosophy.

The author says that "Virtually every hospital in the world uses tracers, and a whole branch of medicine, radiology, deals exclusively in that line." I think he means the field of Nuclear Medicine.