抄録
Improving the method of “colorimetric determination of NL-I of H-V W-M Co.”, a volumetric chemical analysis of naphthalene sulphonats in nickel plating baths was devised.
As naphthalene sulphonate is quantitatively oxidised in hot solution of K2Cr2O7-H2SO4, when heated for 2.5 minutes after the white fume of H2SO4 begins to be generated, chloride ion and second class brighters in nickel baths are also oxidized by K2Cr2O7, so that it is found that there is no trouble in heating naphthalene sulphonates in acidic solution with H2SO4 until the appearence of white fume of H2SO4. Thus the chroride ion and second brighters are eliminated before adding K2Cr2O7.
The both results of “Colorimeter determination of NL-I visual composition method” and this method coincide farely well.
Reproducing of this action is pretty good, and the equivalent of 8 Mol K2Cr2O7 seems to correspond to 1Mol naphthalene sulphonate, regardless of the number of sulphonate radicals.
