Tucked into the advertising pages of this 1904 druggists' formulary — a fat reference volume of "known, admitted and approved" remedies for British chemists — is a boast that would have meant something instantly to any pharmacist of the era, and nothing at all to a modern reader:

THE LEADING HOUSE FOR BLAUD'S PILLS.

The advertiser is shouting about a product so ubiquitous in 1904 that it needed no explanation. Today, almost no one has heard of it. Yet Blaud's Pills may be the most consequential forgotten medicine of the 19th century.

The formula was devised in 1832 by Pierre Blaud, a French country doctor in Beaucaire, who was trying to cure "chlorosis" — the "green sickness" that turned adolescent girls pale, weak, breathless, and prone to fainting. For centuries the condition was blamed on lovesickness, corseting, or "unfulfilled womanhood." Blaud noticed that his patients recovered on a specific pill: ferrous sulfate mixed with potassium carbonate, which reacted inside the pill mass to form ferrous carbonate, protected from oxidation. He reported curing patient after patient in weeks.

He was, without knowing the biochemistry, treating iron-deficiency anemia — the same disorder that today affects roughly a quarter of the world's population and is still the leading nutritional deficiency on Earth.

• The vindication: Chlorosis was not a mysterious female malady. It was iron deficiency, likely driven by menstruation combined with the low-iron diets of urban working-class girls. Blaud was right by roughly seventy years, before hemoglobin's iron content was even understood.
• The scale: By 1900, Blaud's Pills were manufactured by essentially every major British and American pharmaceutical house. The Formulary lists them as a staple counter product. They remained on the British Pharmacopoeia until 1968.
• The disappearance: Chlorosis itself vanished from medical literature around 1930 — not because iron deficiency vanished, but because fortified flour, better diets, and simpler ferrous sulfate tablets replaced the specific diagnosis and its specific pill. The disease and its cure faded together.

What's striking is how close the 19th century came to modern nutritional medicine without the theoretical framework. Blaud didn't know about hemoglobin (identified 1840), had no concept of a "vitamin" or "trace mineral" (both 20th-century ideas), and had no lab test to confirm anything. He worked from bedside observation: pale girl in, pink girl out.

The modern descendant sits on every pharmacy shelf as a $3 bottle of ferrous sulfate. Same active ion, same target condition, same slow correction over weeks. The chemistry hasn't improved much in 190 years — the branding just got less romantic.