QUALITATIVE AND QUANTITATIVE ANALYSIS 



81 



been boiled gently for 15 to 20 minutes, flask F is removed, the 

 solution washed down into the flask, the carbon precipitated 

 by the addition of an excess of 2 iV neutral BaCU solution, 

 and the excess alkah titrated with 0.5A^ HCl solution using 

 phenolphthalein as an indicator. 



Fig. 4.' — Apparatus for determination of total carbon in soil or in solution. 



The absorption flask F is made of a 300-cubic centimeter 

 Erlenmeyer flask, a 1.5 X 25 cm. test tube, and a few glass beads. 

 The bottom of the test tube is drawn out and while still hot the 

 upper part of the constriction is flattened so that two beads will 

 lie over the opening instead of one, so as to facilitate washing out. 



