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Brix hydrometer scale

A hydrometer scale calibrated so that readings at a specified temperature (in the United States, usually 20°C) equal the percentage by weight of sugar in the solution (the number of grams of sugar in 100 grams of liquid). Introduced in 1847 by Adolf F. W. Brix, an Austrian.

The Brix scale is used in sugar refineries, and also often encountered on wine labels where it describes the sugar content of the grape juice from which the wine was made. Each two degrees Brix of the juice leads to about 1% alcohol by volume in the wine. The Balling scale is numerically the same as the Brix.

A. F. W. Brix.
Der Alkoholometer und dessen Anwendung. Ein Handbuch für Eichungs-Behörden, Steuer-Beamte etc. 3rd. edition.
Berlin: Ernst & Korn, Gropius'sche Buch- und Kunsthandlung, 1864.

The first edition was published in Berlin in 1847 by Karl Remarus.

Maple syrup and NIST

The American state of Vermont uses the Brix scale in its famous maple syrup industry, to measure the sugar content of fresh sap. Each hydrometer used must be inspected and approved by a state agency. (The hydrometers used for sap are not the same as the hydrometers used for syrup.)

In 2016, the agency rejected a certain manufacturer's sap hydrometers. The manufacturer protested that their instruments were accurate; it was Vermont's standard that was wrong. Both turned to NIST as an arbitrator.

NIST attempted to outsource the comparison to one of the many competent calibration companies. However, no outside lab wanted the job. The difficulty was temperature. Measurement in degrees Brix are typically made at 68°F or 60°F. But Vermont measures sap at a temperature of 3.33°C (38°F), a typical temperature at sap-gathering time in Vermont. The temperature at which the measurement is made chosen doesn't just effect the density of the sap, it also changes the dimensions of the hydrometer, and oher factors: a nightmare of variables. And so, the full weight of the Fluid Metrology Group of NIST's Physical Measurement Lab was brought to bear upon the maple sap hydrometer. Their conclusion: the Vermont agency's reference hydrometer was accurate; the manufacturer's was off, but NIST supplied them with correction tables.

This may seem like a tempest in a sap bucket, but the value of sap is greatly dependent on its sugar content. A 1°Brix difference in her sap can mean hundreds of dollars to the farmer. And the Vermont agency doesn't just calibrate sap hydrometers for Vermont; it also serves state agencies in other states and even other countries.

How Sweet It Is: NIST Metrology and the Maple Syrup Industry.
NIST Press release, 4 January 2017.

sources

Brix hat 1847 diese Tabellen von Tralles wiederum umgerechnet, indem er zwar dieselbe Temperatur wie Gilpin und Tralles beibehielt, also 60°F. = 15⁵⁄₉ C. = 12⁴⁄₉ R., aber nach Gilpin's Vorgang als Einheit wieder die Temperatur von 60°F. einsetzte und nicht wie Tralles Wasser von der grössten Dichte. Dieses Alkoholmeter von Tralles-Brix ist seit 1847 in Preussen eingeführt.

In 1847 Brix made a fresh version of these tables of Tralles, in which he indeed retained the same temperature used by Gilpin and Tralles, that is, 60°F. = 15⁵⁄₉° Centigrade = 12⁴⁄₉° Reamur, but, following Gilpin's procedure, fixed unity at the temperature of 60°F and not, as Tralles had, at the temperature of water at its greatest density. This alcohol meter of Tralles-Brix has been established in Prussia since 1847.

G. Th. Gerlach.
Über Alkohol und Gemische aus Alkohol und Wasser.
Chemische Industrie, August, 1885. Page 243.