REACTION OF MEAT EXTRACT 



153 



4. Note the amount of ~ NaOH solution required 

 to complete the titration, and add it to the equivalent 

 of the -f NaOH solution previously run in. Take the 

 total as the correct estimation. 



Method of Expressing the Reaction. 



The reaction or litre of meat extract, medium, or any 

 solution estimated in the foregoing manner, is most 



FIG. 99. Stock bottle for deka-normal soda solution. 



conveniently expressed by indicating the number of 

 cubic centimetres of normal alkali (or normal acid) 

 that would be required to render one litre of the solution 

 exactly neutral to phenolphthalein. 



The sign + (plus) is prefixed to this number if the 

 original solution reacts acid, and the sign (minus) if 

 it reacts alkaline. 



