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Early 1900's Concentration Measurements

  1. Sep 6, 2012 #1
    I have read a few papers that were written in the early 1900's where their concentration measurements are M/4, M/8, M/16, M/32, M/256. I am not sure what this means and I was wondering if anyone could relate these concentration measurements to normal concentration measurements we use now, such as Molar. An example of a paper that used this method of measuring concentration is linked below.
    http://ebm.rsmjournals.com/content/23/1/66.extract [Broken]

    I have searched google and had no luck finding what the M/number concentration measurement means. If anyone could find out what this means it would really help.
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Sep 6, 2012 #2
  4. Sep 6, 2012 #3
    The M/4 concentration expression is simply an ordinary molar concentration expressed as a fraction rather than a decimal. So a M/4 concentration really means simply a 0.25 M or a 250 mM solution in modern terms.

    The reason for the fractions being powers of 2 is also a very simple one: It was standard practice to make up a 1 M solution, and then prepare a series of dilutions by pipetting a 50 mL aliquot, and making up to 100 mL in a volumetric flask and then repeating that procedure several times to obtain a M/2, M/4, M/8, M/16 etc. series.
    Last edited by a moderator: May 6, 2017
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