CH. XIII.] TOTAL NITROGEN. 327 



The water in the copper vessel A has previously been vigorously 

 boiled for at least ten minutes to ensure the removal of any ammonia. 

 Remove the flame for a moment and connect the exit pipe of the 

 boiler to C by rubber tubing. Replace the burner. Run in the 

 strong soda from E until the solution is definitely alkaline, as can 

 be seen by the fluid turning blue, due to the formation of cupric 

 hydroxide. The distillation must be allowed to proceed for at 

 least 45 minutes. It is safer to allow an extra half-hour. The only 

 attention necessary is to see that there is a sufficient amount of 

 water in the boiler and that the flask K is at the right height. 



At the end of the operation, remove the blocks from under K, 

 so that H does not dip into the acid. After a few minutes, remove 

 the flame, wash down the interior and exterior of H into K, and 

 titrate as described on p. 323. 



Calculation, see p. 323. 



396. Kjeldahl's method (alcohol distillation). Into a 500 cc. 

 Kjeldahl flask of " Duro " glass measure 2 cc. of the urine, using an 

 Ostwald pipette (fig. 48). Add 3 cc. of pure concentrated sulphuric 

 acid, 2 grams, of potassium sulphate and 2 drops of saturated 

 copper sulphate solution. Heat over a micro-burner, using a Folin's 

 fume-absorber. The flame should be about half an inch in height, 

 and should play directly on the bottom of the flask to ensure boiling. 

 Any particles of carbonaceous matter that form on the side of the 

 flask must be rinsed down into the acid. The heating must be 

 continued for 5 to 10 minutes after the solution has turned blue. 

 Remove the flame and allow the solution to cool until the flask is 

 only pleasantly warm to the hand. Add 20 cc. of distilled water 

 from a measuring cylinder. This should be added rapidly, and the 

 mixture immediately shaken to prevent the formation of a cake of 

 potassium hydrogen sulphate. Cool under the tap. Add three or 

 four pieces of broken porous pot and 15 cc. of 95 per cent, alcohol. 

 Assemble the apparatus, seeing that the clamps are correctly 

 adjusted, so that the rubber stoppers fit into the flasks without 

 undue strain. G is a piece of glass rod, with the lower end flattened 

 out and bent up as shewn. It is passed up through the rubber 

 stopper, and the upper end can then be flattened out, if desired, for 

 convenience of manipulation. The tube is drawn up until the flange 



