l'.H);».J PUBLIC DOCUMENT — No. ai. 127 



;is an assuint'tl acid with a iiioleculai- W('i<;lit (Ictci-iuiiied by for- 

 iiiula (4), or as the acid of any other niolecnlar weight. 



A=^'X"^ (8) 

 5G158 



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 snch cases it is preferable to calculate the percentage 

 directly from the titration by factor .0001 of the molecular 

 w^eight of the acid (mono basic) for an ]^/lO solution, or .001 

 forN/1. 



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

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

 total fatty acids.^ 



A = - (9) 

 n 



Neutral Fat and Unsaponifinhle Matter. — The neutral fat 

 and unsaponifiable matter can be determined by difference, — 

 100 less per cent, of free fatty acids. 



5. Reiciiert-Meissl JSTumbee. 



The Eeichert-Meissl number" indicates the cubic centimeters 



of X/10 potassium hydrate solution required to neutralize that 



])ortion of the volatile fatty acids which is obtained from 5 



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



Leffmann-Beam, Modification. 



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

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

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



Sulfuric acid solution, 1 to 4. 



N/ 10 ])otassium (or sodium) hydrate solution. 



Phenol phthalein solution, 1 gram to 100 cubic centimeters of 

 alcohol, neutralized. 



1 strictly it should be the neutralization num])er of the free fatty acids. The nuniV)er of 

 cubic centimeters of N/l alkali rcfiuired can be substituted in itlace of the values a and n. 



» The Reichert number is that obtained from 2.5 prams of f;it, and the i>r()portion of acids 

 volatilized is somewhat gre;iter than with 5 grams, Reichcrt-Meissl number. 



