A-2 



Tin At lii(isj)h< ir iij I Ik Soil 



Atmli/nis of noil air. The large t\'pe of Haldaiie's gas apparatus is 

 used. The measuring tube {A. Fig. Hi) lias a capacity of 21 c.c. and 

 is graduated finiii 15-21 c.c. into 0-01 c.c. The analysis of the gas is 

 carried out under constant pressure: temperature and water va|K)ur 

 pressure are compensated by the bulb shown to the left. The water in 

 the jacket must be thoroughly mi.Ked before readings are taken : this is 

 done bv blowing though it air from foot bellows. .V laboratory vessel (B) 



Fig. 10. Apjjaratiis for the aniilysis of soil iiir. 



in a poicelain mercury trough (C) [as used in the well-known Bone and 

 Wheeler gas apparatus] is attached to the measuring tube and filled 

 with mercury by connecting with an evacuated flask (D) provided with 

 a mercury trap (S). Through this laboratory vessel the gas is readily 

 introduced into the measuring tube. The analysis proceeds in the 

 usual wa}'. Finally the residual gas is forced by moans of the levelling 

 tube (E) into the laboratory vessel nnd ejected. A small telescope 



