[13] Ibid., Table I.
[14] Methods of Analysis of the Association of Official Agricultural Chemists (1919).
[15] All specific gravities given in this bulletin are on a 20°C/20°C basis.
[16] This counterpoise may be prepared with a can or bottle weighted with some heavy material such as solder or shot, until it balances approximately the weight of the can full of pulp. The counterpoise, once prepared, may be left in the centrifuge.
[17] If it is preferred a chemical thermometer with Centigrade scale may be used having a range of from 0 to 100 degrees.
[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.
[19] These temperature corrections are for a Brix instrument standardized for 20°C. There are Brix hydrometers on the market standardized for 17.5°C. Temperature corrections for a Brix hydrometer standardized at this temperature may be obtained by correcting to 20° by means of the above table (for instrument graduated at 20°C.) and adding to this corrected reading 0.12. For instance suppose the reading for a 17.5° instrument is 7.00 at 25°C. The correction from the above table will be .28 or a total of 7.28. Adding .12 to this gives a corrected reading of 7.40. If the reading is 7.00 at 15°C. the correction from the above table amounts to .22 (to be subtracted) giving 6.78. Adding 0.12 to this gives the corrected reading of 6.90.
[20] This table gives the per cent of total solids contained by pulp of different specific gravities varying from unconcentrated pulp as it comes from the cyclone to the highly concentrated product.
[21] Geerlig’s table for dry substance in sugar house products by Abbé refractometer at 28°C.