ESTIMATION OF NITRATES 



III 



soda is weighed out accurately and washed into the 

 funnel d by means of 2 to 4 c.c. of water. When the 

 material is dissolved the funnel is connected to the 

 tube A, and by cautiously lowering 

 B the liquid is drawn into the nitro- 

 meter. The funnel is washed out 

 with I C.C. or so of water from a 

 wash-bottle with a fine jet, and the 

 washings also drawn into A. The 

 sides of the funnel are now rinsed 

 with 3 to 4 C.C. of concentrated 

 H2SO4, which is then passed into 

 the tube by lowering B. This is 

 quickly repeated twice with small 

 quantities of sulphuric acid, the 

 tap being closed immediately the 

 washings have been transferred. 

 If any air is enclosed duriiig these 

 operations it must be- immediately 

 removed by raising B slightly, 

 gently opening the tap and closing 

 it again when the air has escaped. 



The graduated tube is now un- 

 damped, the connecting rubber 

 pinched between the fingers close 

 to the lower end of A, and the 

 latter inclined in both hands 

 almost horizontally and with a 

 quick motion brought back to the 

 vertical. The process is repeated 

 minutes so that the mercury 

 mixed. 



Fig. 18.— The Lunge 

 nitrometer. 



for 

 and the 



two or three 

 acid are well 

 The tubes are then adjusted in the clamps so 

 that the mercury is approximately level in both limbs, 

 and the apparatus allowed to stand till the temperature 

 coincides with that of the room. 



