V. 



THE ANALYSIS AND COMPOSITION OF SOILS 



87 



When the operation is over, the rubber at K is disconnected ; the 

 cork is loosened from F ; E and G are rinsed oub by distilled water 



FIG. 5. Determination of Nitrogen 



A is the flask in which the soil has been heated with the sulphuric acid. 



B is a similar flask containing water and a scrap of granulated zinc so as to en- 

 sure a steady evolution of steam. This flask is fitted with a safety tube so that the 

 pressure in the apparatus can be determined at once (by the height of the water in 

 this tube). 



C is a separating funnel, bent so as to fit properly and containing the strong 

 potash solution. 



D is a bulb on the delivery tube, with an arrangement for preventing any 

 particles of the solution in A from being carried over by the steam. 



E is a 50 or 100 cc. pipette, which acts as a condenser to some extent and pre- 

 vents any standard acid being drawn back if the evolution of steam be suddenly 

 stopped. 



F is an 8 oz. conical flask. 



G is a tube shaped as shown and filled with glass beads through which the 

 standard acid has been allowed to run into F. 



into F ; a little (one or two drops) methyl orange solution is added ; 

 and decinormal caustic soda solution is run in from a burette until the 

 red colour just disappears. The amount of ammonia and hence of 



