PRACTICE X 



DETERMINATION OF THE INORGANIC CARBON (OR LIMESTONE 



PRESENT) IN A SOIL 



ITse the apparatus referred to in Practice XXX for organic carbon. 



Place from 2 to 10 g. of soil, according to the amount of carbonates 

 present, in the Erlenmeyer flask. Connect with the apparatus and 

 bring in slowly through the separately funnel an excess of dilute 

 (1 : 1) hydrochloric acid. After the reaction is over, boil the contents 

 of the flask to drive out dissolved carbon dioxid, fill with water 

 through the separatory funnel, measure the volume of gas in the 

 burette, and pass same into an absorption pipette containing a 33 per 

 cent solution of potassium hydroxid. Eeturn the unabsorbed gas to 

 the burette and read off its volume. The difference between the 

 readings is carbon dioxid, whose volume must be corrected for tem- 

 perature and pressure. 



(1) (2) 



cc. of CO 2 



Barometer and temperature 



Weight of C equivalent 



Weight of CaCO 3 equivalent 



Per cent of CaCO 3 present _ 



Average 



Calculate the results obtained in Practices IX and X, and with 

 these record the results obtained by three members of each group as 

 indicated upon the following page. Consider 6 acre-inches of normal 

 soil to weigh 2,000,000 pounds. 



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