0° 0.999871 21° 0.998047 1° 0.999928 22° 0.997826 2° 0.999969 23° 0.997601 3° 0.999991 24° 0.997367 4° 1.000000 25° 0.997120 5° 0.999990 26° 0.996866 6° 0.999970 27° 0.996603 7° 0.999933 28° 0.998331 8° 0.999886 29° 0.995051 9° 0.999824 30° 0.995765 10° 0.999747 31° 0.995401 11° 0.999655 32° 0.995087 12° 0.999549 33° 0.994765 13° 0.999430 34° 0.994436 14° 0.999299 35° 0.994098 15° 0.999160 36° 0.993720 16° 0.999002 37° 0.993370 17° 0.998841 38° 0.993030 18° 0.998654 39° 0.992680 19° 0.998460 40° 0.992330 20° 0.998259 From the table and the weight of water found, the volume of the pyknometer is easily calculated. _Example._—Let the weight of water found be 11.72892 grams, and the temperature 20°. Then the volume of the flask is equal to 11.72892 ÷ 0.998259, _viz._, 11.95 cubic centimeters. =50. Use of Pyknometer at High Temperatures.=—It is often found desirable to determine the density of a liquid at temperatures above that of the laboratory, _e. g._, at the boiling-point of water. This is easily accomplished by following the directions given below: _Weight of Flask._—Use a small pyknometer of from twenty-five to thirty cubic centimeters capacity. The stopper should be beveled to a fine edge on top and the lower end should be slightly concave to avoid any trapping of air. The flask is to be thoroughly washed with hot water, alcohol and ether, and then dried for some time at 100°. After cooling in a desiccator the weight of the flask and stopper is accurately determined.[27] [Illustration: FIGURE 28. BATH FOR PYKNOMETERS.] _Weight of Water._—The flask in an appropriate holder, Fig. 28, conveniently made of galvanized iron, is filled with freshly boiled and hot distilled water and placed in a bath of pure, very hot distilled water, in such a way that it is entirely surrounded by the liquid with the exception of the top.