KJELDAHLS PROCESS. 



165 



Process : A. Incineration. 10 cc of urine are measured from 

 a burette into a hard glass flask, to this add 15 cc sulphuric 

 acid, 10 g- potassium sulphate and 0*5 g - of sulphate of copper 

 crystals. K 2 SO 4 raises the 

 boiling point, and CuSO 4 

 helps oxidation. Close the 

 mouth with a loose balloon 

 stopper, and support the 

 flask on wire gauze with 

 the neck in an inclined 

 position. Raise the heat 

 gradually and boil until 

 the blackened fluid be- 

 comes quite clear (green 

 from the CuSOJ. This 

 step must be carried out 

 in a draught chamber on 

 account of the sulphurous 

 fumes which are given off. 

 When quite cool add 

 slowly 50 cc distilled water. 

 As this is attended by 

 much heating cool again. 

 Add a few drops of methyl 

 orange and half a tea- 

 spoonful of talc. Next 

 add caustic soda to liber- 

 ate the ammonia, pouring it along the side of the vessel until 

 the reaction is nearly alkaline, cool, render alkaline by a further 

 addition of NaOH, and connect at once with the distilling 

 apparatus, which has meanwhile been prepared. 



l l am indebted to my colleague Prof. Proctor's work, "Leather Industries," 

 for the method of distillation without a condenser, and to his assistant, Dr. 

 Guthrie, for the more recent modifications in the apparatus. 



FIG. 18. Apparatus for Kjeldahl's Process. 1 



A Hard Jena or Bohemian glass. B Bulb 

 to prevent spurting over of alkali during distil- 

 lation. C Erlenmeyer flask surrounded by a 

 cooling vessel containing water. D Tube 

 containing glass beads or broken glass. E To 

 arrest regurgitation. E and B are made out 

 of pipettes. 



