The apparatus is assembled as shown

The apparatus is assembled as shown in Fig. 27. Ammonia gas from a commercial cylinder (Note 1) enters the system at K. R is a mercury trap which would serve as a safety valve if the system should become blocked by solidification of the amide owing to an accidental drop in temperature. J is a U-tube containing just enough mercury to seal the bend, and it serves to estimate the rate of ammonia flow. I is a Kjeldahl trap which prevents any mercury from being thrown into the fusion pot A, which (Note 2) is conveniently supported on a tripod set on bricks to raise it to a convenient height above the burner M. Through the cover of the fusion pot passes an outlet tube B, a thermometer well T, and the combined inlet tube CDE. The thermometer well is welded shut at the bottom and projects about 6 mm. below the wider inlet tube, to which it is welded at the top. A gland or packed joint O, through which the inlet passes, is packed with a few turns of asbestos cord, the upper hexagonal nut being turned down with a wrench so that ammonia will not escape past the packing and so that there will be sufficient resistance to hold CDE in any position to which it may be raised (Note 3). The rubber tubes H, H' should be of sufficient length (5–7 cm.) to be very flexible and facilitate manipulation of the hot cover. The outlet tube B is at least 10 mm. in diameter.