Abstract: A method and suitable apparatus for periodically analyzing pulp stock, including wood pulp and water, in a pulp digester, to determine the amount of cooking to which the pulp has been subjected. The method includes taking a sample of the pulp stock from the digester, diluting the sample to a predetermined range of consistency, and determining the exact consistency of the sample. Next, the sample is transferred to a reaction chamber. A reagent is then added to the sample and allowed to react with the sample at a predetermined temperature. The light absorbance of the reagent during the reaction is continuously monitored during the reaction. After the light absorbance has clearly passed a peak, the value of the peak is combined with the consistency of the sample, previously determined, to arrive at the amount of cooking to which the sample had been subjected prior to the test, from a known relationship thereof to the light absorbance of the reagent and the consistency of the sample.

Abstract: A method and suitable apparatus for periodically analyzing pulp stock, including wood pulp and water, in a pulp digester, which may or may not be part of a paper machine, to determine the amount of cooking to which the pulp has been subjected. The method includes diluting a sample of the pulp stock from the digester, diluting the sample to a predetermined range of consistency, and determining the exact consistency of the sample. Consistency can be determined by any suitable commercially available apparatus. Next, substantially all the water is removed from the sample. A reagent, preferably a 14 percent solution of nitric acid in water, is then added to the sample and allowed to react with the sample for a predetermined time interval at a predetermined temperature. The light absorbance of the reagent during and after the reaction is determined by the amount of cooking to which the pulp has been subjected and the consistency of the sample.