IMPROVED METHODS FOR FAT ANALYSIS. 



Ill 



multiplied by 1.1, minus the blank, and reduced to a 5-gram fat basis, 

 is the Reichert-Meissl number. 



Limit of error, 0.25 cubic centimeter. 



Srjnopsis of Reaction. 



(RCOO)3C3H6+3 KOH= 3 RCOOK+ CsHsCOH)^ 

 fat alkali salt glycerol 



The glycerol acts as a transmitter of heat, having a boiling point of 

 290° C. 



2 RCOOK+ H2SO4 = 2 RCOOH+ K2SO4 



Distillation of the volatile acids. Titration. 



Swpplevientary Notes. — As this method is only an arbitrary one it is 

 essential to adhere strictly to the conditions of operation as laid down if 

 comparative results are to be obtained, and by so doing over 80 per cent, 

 of the soluble acids in butter can be secured in the distillate. Jensen 

 states that the Reichert process ^ yields with butter fat 85 to 88 per cent, 

 of the total butyric, 24 to 25 per cent, of the caprylic, and 85 to lOO per 

 cent, of the capj^ic acids. Repeated distillation yields higher results, but 

 is accompanied by decomposition of the nonvolatile acids. Glycerol 

 potash is preferable to alcoholic potash in that it shortens the process 

 and prevents possible loss due to the formation of esters during saponifi- 

 cation. Sodium hydroxide has greater basicity than potassium hydroxide, 

 but the resulting hard soap is less soluble. The fatty acids appear to have 

 practically the same affinity for both hydroxides. 



Acetic, butyric, valeric, caproic, caprylic and capric are the only fatty 

 acids that can be distUled under ordinary pressure without decomposi- 

 tion. These acids have comparatively high boiling points, as shown by 

 the following table, but owing to their high vapor tension they can be 

 readily distilled from aqueous solutions with steam, and are termed "vola- 

 tile" acids: — 



The boiling points rise with the increase in molecular weight. Laurie 

 acid is very slightly volatile in a current of steam. The nonvolatile acids 

 when distilled at ordinary pressure undergo partial decomposition and 



1 Ztschr. Unterauch. Nahr. u. Geaussmtl. 1905, p. 272. 



