One of the most famous figures in the history of alcohol — 40 degrees — acquired its author retroactively, half a century after it came into being.
Until the mid-19th century, the Russian Empire measured the strength of bread wine by methods that would make a modern metrologist’s eye twitch. The Drinking Tax Statute of 1817 prescribed two methods. The first was shaking: a bottle was shaken and the bubbles counted. Large ones that burst quickly meant weak spirit; small, persistent ones meant strong. The second was burn-off in special testing vessels: a portion of wine was set alight, and they watched how much liquid remained after the alcohol had burned away. If exactly half remained, there before you was “polugar,” the basic strength standard — roughly 38% alcohol by volume. Polugar was the benchmark for trade: wine stronger than it cost more, weaker wine less. The system worked, but it worked the way a market steelyard works: crudely, with plenty of variation, and every official could “recalculate” it his own way.
The problem was neither one of taste nor chemistry — it was fiscal. The state sold the right to trade in alcohol through a tax-farming system, and every percentage point of strength meant rubles for the treasury. When strength is judged by eye from bubbles, the treasury loses money on every barrel. What was needed was an instrument, not eyeballing.
On February 10, 1843, the Governing Senate issued a decree that quietly overturned the entire system of alcohol accounting in the country. The Tralles alcoholometer was introduced everywhere — an instrument already known in Europe, but adapted to Russian conditions under the direction of Academician Germain Henri Hess. Hess — the very Hess whose law of constant heat summation is still taught in first-year chemistry courses — designed an instrument that showed how many buckets of water had to be added to spirit to produce polugar. Later, in 1847, he published a book, “The Accounting of Spirits,” which became a practical guide for excise officials.
What happened to the number? The Tralles alcoholometer worked in percentages by volume at a specified temperature. Polugar — an old measure tied to burn-off — corresponded to roughly 38% alcohol by volume, and after the excise reform of 1863, 38° on the Tralles scale became the mandatory strength of ordinary bread wine. The round standard appeared later: in October 1866, Finance Minister Mikhail Reutern submitted a proposal to the State Council on the mandatory strength of retail wine; on December 6, 1866, the new version of the article received imperial approval — and from 1868, the law required “not less than 40 degrees on the Tralles alcoholometer.” It was an accounting decision: a round number makes taxes easier to calculate, instruments easier to calibrate, underproof liquor easier to penalize. Nobody was looking for the point of perfect taste. They were looking for the point where the interests of the treasury, the capabilities of measuring equipment, and the habits of the market converged.
What wins me over in this story is precisely its prosaic nature. A great number was born not in a laboratory and not in a cellar — it was born in an office.
An alcoholometer is a temperamental thing. Glass is uneven, temperatures fluctuate, spirit behaves differently in winter Arkhangelsk and summer Odesa. When on January 1, 1863, the tax-farming system was replaced with a purely excise-based one — that is, when the state stopped selling the right to trade and began taxing every degree of spirit produced — precision in measurement became a matter of national scale. Academician Adolph Theodor Kupffer, director of the Central Depot of Standard Weights and Measures, took on a task whose scale resembles military logistics more than science.
The Ministry of Finance ordered 15,000 glass alcoholometers. Every one had to be verified — checked to ensure that the readings of a particular tube matched the standard. Kupffer refined the Tralles tables, calculating corrections for the low temperatures characteristic of the Russian climate. In essence, he created an infrastructure: without his tables and verified instruments, the excise system would have been a fiction — like scales without weights. All this work was taking place alongside scientific research into alcoholic solutions, and it is here that the young Dmitri Ivanovich Mendeleev enters the stage.
For the research needs of the Department of Non-Assessed Revenues, Kupffer and Mendeleev received from a state warehouse fifteen buckets of bread spirit at a strength of 71.6% by weight — by compulsory order of the department director; this was the very batch distilled in the laboratory of the Institute of Railway Engineers. By then, Mendeleev had already written the section “Alcohometry” for the third issue of “Technology According to Wagner” (that was in 1862), so the subject was familiar to him. But he was not interested in a drink recipe. He was interested in what happens when alcohol meets water at the molecular level.
The question sounds simple: mix a liter of alcohol with a liter of water — do you get two liters of solution? No. The volume will be less than two liters. When mixed, water and ethanol molecules pack more tightly than they do separately — what occurs is known as contraction. The extent of this contraction depends on proportion, temperature, and the purity of the components. Mendeleev wanted to measure it with maximum precision across the entire range of concentrations — from pure water to anhydrous alcohol.
In November 1864, he presented, and in January 1865 defended, a doctoral dissertation with a title that sounds dry and precise in itself: “A Discourse on the Combination of Alcohol and Water.” Five chapters: on the contraction of solutions, on determining specific gravities, on anhydrous alcohol, on maximum contraction, on changes in specific gravity during mixing. On the basis of his own pycnometer measurements, Mendeleev assigned anhydrous alcohol a specific gravity of 0.78945 (at 20°C, relative to water at its maximum density) — the 0.7899 is merely his recalculation of Lovitz’s data, and even that alcohol he did not consider anhydrous. The dissertation is a work of physical chemistry, metrology, painstaking labor. The word “vodka” does not appear in it. There is no recommendation on beverage strength. There is no conclusion that 40% is some special, “ideal” point.
A solution of 40% ethanol and 60% water is indeed an unusual liquid, but not unusual in the sense suggested by the myth. At room temperature, its viscosity is roughly three times higher than that of either pure water or pure alcohol. When frozen, its viscosity rises by another 2.5 times compared with room temperature. Its freezing point is substantially below zero, which makes the solution convenient to store in a cold climate — and useful for certain technical applications. Leave a glass of vodka open on the table, and over two days its strength will fall from 40% to roughly 30%: alcohol evaporates faster than water, and the proportion shifts.
All these properties are consequences of the molecular interaction between ethanol and water, of those same hydrogen bonds and cluster structures that Mendeleev began to probe in his dissertation. But the greatest contraction of the solution — maximum contraction — occurs not at 40%, but at another concentration. Mendeleev knew this and described it. The coincidence of the state standard with some special physical point is a construction that has to be assembled from pieces belonging to different sets — and it does not come together.
The legend began to crystallize in the early 20th century, when the Russian Empire introduced a state vodka monopoly and needed a narrative that would give its state product a scientific sheen. By then, Mendeleev was a living icon of Russian science — creator of the periodic table, government consultant on industrial matters, a figure whose authority could sanctify anything. Linking his name to vodka — a drink already regarded as a national symbol — was an almost inevitable gesture.
After that, the myth lived by its own laws. In 1991, culinary historian William Pokhlyobkin published a book, “The History of Vodka,” in which Mendeleev’s connection to the forty-degree standard was presented as an established fact. The book became a bestseller and a reference work for journalists, marketers, and tour guides. Commercial brands picked up the legend: portraits of Mendeleev appeared on labels, along with references to his dissertation and phrases such as “made to the recipe of the great chemist.” The chronology bothered nobody — though all it takes is placing two dates side by side, 1843 (the Senate decree) and 1865 (the dissertation defense), to see that the standard is twenty-two years older than the “recipe.”
One more detail that never fails to amuse me: Mendeleev himself did not drink vodka. For family reasons — a phobia connected to alcoholism in his family — he preferred red wine. The man whom a century and a half later they made the father of the national drink kept that drink at arm’s length.
A convenient number, a great name, a national product — three ingredients which, when mixed, yield a solution stronger than any alcohol. A myth does not need chronology; it needs an internal logic that feels right. “A great chemist calculated the ideal proportion” is a story people want to tell at the table. “Finance Ministry officials rounded polugar off to a convenient number for calculating excise duties” — not so much.
And yet the real story is no less gripping; it simply has different protagonists. Hess, who adapted a European alcoholometer for a country where strength was measured by setting liquor on fire. Kupffer, who organized the verification of thousands of fragile glass instruments across a continental empire. The anonymous excise officials who needed a number divisible without remainder. And Mendeleev, who truly did study alcoholic solutions — but studied them the way one studies physics, not the way one composes recipes.
The 40-degree standard remains the norm for Russian vodka today — GOST reproduces it. Mendeleev’s dissertation remains a significant work in the physical chemistry of solutions. And the legend of their connection lives apart from them both — and, judging by the labels in any shop, has no intention of surrendering.