IDOD.J PUBLIC DOCUMENT — No. 31. 127 



as an assumed acid with a molecular weight determiued by for- 

 mula (4), or as the acid of any other molecular weight. 



^_aXm ^g^ 

 56158 ^ 



When the free acid is known or the predominant acid is a mix- 

 ture, it is often desirable to report acidity in terms of that 

 acid. In such cases it is preferable to calculate the percentage 

 directly from the titration by factor .0001 of the molecular 

 weight of the acid (mono basic) for an N/lO solution, or .001 

 for N/1. 



The per cent, of acidity (A) can also be calculated from the 

 acid number (a) and the neutralization number (n) of the 

 total fatty acids. ^ 



A = - (9) 

 n 



Neutral Fat and U nsaponifable Matter. ■ — The neutral fat 

 and unsaponifiable matter can be determined by difference, — 

 100 less per cent, of free fatty acids. 



5. Reicjiert-Meissl ISTumbee. 



The Reichert-Meissl number- indicates the cubic centimeters 



of N/10 potassium hydrate solution required to neutralize that 



portion of the volatile fatty acids which is obtained from 5 



grams of an oil, fat or wax by the Eeiehert distillation process. 



Leffmann-Bcam Modification. 



Reagents. — Glycerol-soda solution, 100 cubic centimeters of 

 sodium hydrate solution (equal parts of soda and water filtered), 

 free from carbonate, to 900 cubic centimeters of pure glycerol. 



Sulfuric acid solution, 1 to 4. 



N/ 10 potassium (or sodium) hydrate solution. 



Phenolphthalein solution, 1 gram to 100 cubic centimeters of 

 alcohol, neutralized. 



1 strictly it should be the neutralization number of the free fatty acids. The number of 

 cubic centimeters of N/1 alkali required can be substituted in place of the values a and n. 



2 The Reichert number is that obtained from 2.5 grams of f.it, and the proportion of acids 

 volatilized is somewhat greater than with 5 grams, Reichert-Meissl number. 



