ANALYTIC PROCESSES 23 



Standard acid. — ^/^ Sulfuric or hydrochloric 

 acid, the strength of which has been accurately 

 determined. 



Standard alkali. — ^/jo Ammonium hydroxid, so- 

 dium hydroxid, or barium hydroxid, the strength 

 of which in relation to the standard acid must 

 be accurately determined. 



Sodium hydroxid solution. — 500 grams should 

 be added to 500 c.c. of water, the mixture al- 

 lowed to stand until the undissolved matter 

 settles, the clear liquor decanted and kept in a 

 stoppered bottle. It will be an advantage to 

 determine approximately the quantity of this 

 solution required to neutralize 20 c.c. of the 

 strong sulfuric acid. 



Indicator. — Cochineal solution is recommended 

 by the A. O. A. C, but methyl-orange and sodium 

 alizarin-monosulfonate are satisfactory. Methyl- 

 orange solution should be very dilute; i part in 

 lobo. A drop is sufficient for 100 c.c. of liquid. 

 Phenolphthalein is not well adapted to tritation 

 of ammonium compounds. 



Digestion and distillation flasks. — Jena-glass 

 round-bottomed flasks with a bulb 12.5 cm. 

 long and 9 cm. in diameter, the neck cylindrical, 

 IS cm. long and 3 cm. in diameter, flared slightly 

 at the mouth. 

 Process 



S c.c. of the sample are placed in a digestion 

 3 



