Mathematical Table, Brinemaster dial-a-brine

By the mid-20th century, industrial chemists had introduced a form of hydrometer for measuring brine strength from the density of a water/salt solution at a known temperature. This rotating table allows one to find the chemical properties of solutions of sodium chloride (common table salt) in water at a temperature of 60 degrees Fahrenheit in degrees of the “salometer scale.” By definition, the salometer degree indicates percentage of saturation of a salt solution. For example, a reading of 70 indicates 70% saturation. Hence the scale runs from 0 to 100.

The slide chart consists of two paper discs of the same size, with a third slightly larger disc between them. The middle disc is elongated at one end and has a hole so that it may be suspended. A metal rivet holds the discs together at the center. Cutouts in the two smaller discs allow one to read tables printed on the central disc. The front of the instrument has tables for 0 to 50, and the reverse for 51 to 100. For each salometer degree, the table lists such chemical properties of the solution as its specific gravity, the percentage by weight of sodium chloride, the weight in pounds of one gallon of brine, the number of pounds per gallon of brine of both sodium chloride and water, the weight of one cubic foot of brine, the number of pounds per cubic foot of both sodium chloride and water, the number of gallons of water per gallon of brine, the number of pounds of salt per gallon of water, and the freezing point in degrees Fahrenheit. Another table indicates how one should adjust readings in degrees salometer when measurements are taken at temperatures other than 60 degrees Fahrenheit.

A mark on the top disc reads: BRINEMASTER (/) dial-a-brine. A second mark there reads: Diamond Crystal Salt Company (/) ST. CLAIR, MICHIGAN. A mark on the bottom disc reads: Slide-Chart Copr. [sic] 1962, PERRYGRAF Corp., Maywood, Ill.

The salinity of brines was expressed in salometer degrees from at least the 19th century.

References:

L. C. Beck, “Report on the Mineralogical and Chemical Department of the Survey,” In Assembly: State of New York, Issue 150, 1841, p. 18.

E. Meriam, “American and Foreign Salt,” Sixth Annual Report of the American Institute of the City of New York, 1848, p. 207.

A. D. Morrison-Low, “Hydrometer,” Instruments of Science: An Historical Encyclopedia, eds. R. Bud and D. J. Warner, New York & London: Garland Publishing, 1998, pp. 311–313.

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