Note 208 — FOREWORD
Reading edition
The presence of pure acetylsalicylic acid does not seem to affect the iron (Fe+++) salicylic acid coloration. The small amount of acetic acid was added to the sodium salicylate control solution (1) to stimulate an acidity approximating the acidity of the acetylsalicylic acid, and (2) since acetylsalicylic acid gives by hydrolysis both acetic acid and salicylic acid, it was thought advisable to add acetic acid to the standard. If there is any free acetic acid in a sample of acetylsalicylic acid containing salicylic acid (which I believe is generally the case when salicylic acid is present) then it would modify the color given by the same amount of salicylic acid alone. For this reason it was thought to be more comparable to have the standard contain a slight amount of acetic acid.