5.—5.1 Distillation apparatus. See Method 2.
5.2 Apparatus for the determination of ammoniacal nitrogen according to analytical technique 7.2.5.3. An example of recommended apparatus is reproduced in Figure 6 in the Appendix.
The apparatus is made up of a specially shaped receptacle with a ground glass neck, a side neck, a connecting tube with a splash head and a perpendicular tube for the introduction of air. The tubes can be connected to the receptacle by means of a simple perforated rubber bung. It is important to give a suitable shape to the end of the tubes introducing air, since the bubbles of gas must be evenly distributed throughout the solutions contained in the receptacle and the absorber. The best arrangement consists of small mushroom-shaped pieces with an external diameter of 20 mm and six openings of 1 mm around the periphery.
5.3 Apparatus for the estimation of urea nitrogen according to the urease technique (7.2.6.1).
It consists of a 300 ml Erlenmeyer flask, with a seperating funnel and a small absorber. An example of recommended apparatus is reproduced in Figure 7 in the Appendix.
5.4 Rotary shaker, 35-40 turns per minute.
5.5 pH meter.
5.6 Laboratory oven.
5.7 Sintered glass crucibles, diameter of pores 5 to 15 microns.