Millimeters tension of aqueous vapor for KOH solutions of | +----------------------------+-------------------------+ Temperature. | 9.09 per 16.66 per 23.08 per 28.57 per 32.89 per | cent. cent. cent. cent. cent. 10°.00 8.62 8.01 7.31 6.50 5.62 11°.00 9.21 8.56 7.82 6.95 6.01 12°.10 9.90 9.21 8.41 7.47 6.46 13°.00 10.50 9.77 8.92 7.93 6.86 13°.95 11.17 10.39 9.49 8.44 7.30 15°.15 12.06 11.22 10.25 9.11 7.86 16°.00 12.74 11.85 10.82 9.62 8.33 17°.00 13.57 12.63 11.54 10.26 8.88 18°.00 14.46 13.45 12.29 10.93 9.47 19°.00 15.39 14.33 13.09 11.65 10.09 20°.00 16.38 15.25 13.93 12.40 10.75 21°.00 17.42 16.22 14.82 13.20 11.44 21°.82 18.32 17.06 15.59 13.88 12.04 23°.00 19.68 18.32 16.75 14.92 12.94 24°.00 20.92 19.47 17.80 15.86 13.76 25°.00 22.19 20.67 18.91 16.85 14.62 26°.00 23.55 21.94 20.07 17.89 15.53 26°.98 24.95 23.25 21.27 18.96 16.46 27°.93 26.38 24.59 22.51 20.07 17.45 29°.00 28.08 26.18 23.96 21.38 18.59 30°.00 29.76 27.74 25.40 22.67 19.72 31°.00 31.51 29.38 26.91 24.03 20.91 32°.13 33.61 31.34 28.72 25.65 22.34 33°.00 35.30 32.93 30.18 26.97 23.50 34°.00 37.34 34.84 31.94 28.56 24.89 =166. Use of Volumetric Method.=—For practical purposes it may be said that the volumetric determination of nitrogen in fertilizer analysis has gone entirely out of use. For control and comparison it is still occasionally practiced but it has had to give way to the more speedy and fully as accurate processes of moist combustion with sulfuric acid which have come into general use in the last decade. The student and analyst however should not fail to master its details and become skilled in its use. There are certain nitrogenous substances such as the alkaloids which are quite refractory when subjected to moist combustion. While such bodies may not occur in fertilizers it is well to have at hand a means of accurately determining their nitrogen content.