The writer discusses about the following items : origins of pitch, conditions of trouble in various mill spots, preventive methods, etc., referred to wood species, structure and properties of woods, chemical compositions of pitches, digestion degree of pulp, and other mill practices.And the gist of his paper is as follows :
1.The origin of trouble may be attributed to the fats in pith cells and resin duct cells.
2.Notwithstanding being less different from resin quantities between red pine and Todo, from the analytical point of view, the trouble seems to be the worse in the former.
3.Occurrence of pitch troubles may be affected by such factors as properties of fats in resin, strength of cell membrain and penetrability of cooking liquid.
4.Some experimental results upon the changes in quality and quantity of extractive pitch by seasoning and examples of analytical values of the pitch are tabulated.
5. Explanations of pitch troubles occurred at various mill spots.
