CH. XIII.] 



TOTAL NITROGEN, 



325 



flask, E, of about 400 cc. capacity, place 20 cc. of standard 

 sulphuric acid, about 0*2 N. 



This flask is then placed on an ad- 

 justable stand, so arranged that the lower 

 end of the tube D dips below the surface 

 of the acid in E. The bulb in D is to 

 decrease the risk of the acid in E being 

 sucked back by a sudden cooling of A 

 during the distillation. D is connected 

 to a condenser C. The best pattern is 

 Davies', which is shewn in fig. 40. 



To the flask A add 35 to 40 cc. of 

 40 per cent, sodium hydroxide, pouring 

 it down the neck and wall of the flask 

 so as to form a bottom layer ; loss of 

 ammonia is thus prevented. 



Fit the glass tube B into the neck 

 of A by means of a well-fitting rubber 

 stopper. The special bulb on B is to 

 prevent any of the alkaline fluid bumping 

 over into the distillate. 



Mix the contents of A by shaking 

 and immediately connect up B with C 

 by means of another well-fitting rubber 

 stopper. Heat the mixture in A to boil- 

 ing by means of a free flame from a 

 Bunsen burner provided with a rose-top. 

 Allow the fluid to boil till at least half 

 the total volume of fluid has distilled 

 over, lowering E from time to time, so Fi g- 4- Kjeidahl appara- 

 that D does not dip too far under the r s ect bS^*' 

 acid. Finally, lower E so that the tube 



no longer dips under the surface and continue the boiling for 

 another minute or two to wash down any of the standard acid 

 that may have been sucked up into the tube or bulb. Wash 

 down the exterior of the lower end of D with a jet of distilled water, 

 allowing the washings to run into E. 



