1528 | 1.0519 | | 1.0509 | 1.0514 Do | | | 1.0485 | 1.0514 1530 | 1.0252 | | 1.0281 | 1.0260 Do | | | | 1.0264 Do | | | | 1.0269 1531 | 1.0291 | | 1.0312 | 1.0294 Do | | | | 1.0311 Do | | | | 1.0313 ------+---------------+---------------+---------------+-------------- [18] Table 7 gives the results obtained in the determination of specific gravity of several samples of pulp by different methods. The specific gravity given in the first column under the head “Centrifuging at 68° F.” has been proved to be correct by other analytical methods. It will be noted that where duplicate determinations are given in this column they agree with each other very closely. The errors in the other methods in determining specific gravity are shown in the remaining columns. It will be noted that the duplicates given in these columns vary materially from each other. It should be stated that the results given under the heading “Pouring cold and whirling by hand” were obtained by much more careful work than is practicable in the factory. The flasks in which the determination was made were equipped with a bail, as shown in Fig. 5. page 44, and the samples were whirled by hand until air bubbles were eliminated as far as practicable by that method. The results, in this column are therefore much more accurate than are obtained by the method as ordinarily practiced. It was thought that better results might be secured by modifying the construction of a cup in such a manner as to permit it to be filled by dipping below the surface of the pulp in the kettle. A bail made of 3/16-inch wire was, therefore, soldered to the opposite side of the cup (see Fig. 5). By means of the bail the cup was lowered into the kettle. After it was filled with the pulp the attempt was made to remove air bubbles by repeatedly giving the bail a quick twist or circular motion with a sudden stop. The cup was then brought quickly to the surface of the kettle and “struck off” with a straight edge, the outside of the cup and bail washed quickly with water, dried, and the cup and contents weighed.