CH. Xl] FATS. 263 



(1) heat with fragments of acid potassium sulphate 

 for several minutes. 



Glycerin gives a very pungent acrid characteristic 

 smell (smell of acrolein). 



(2) Add a few drops of copper sulphate solution 

 and then excess of potash solution. 



If glycerin is present a deep blue liquid is produced 

 instead of precipitate of cupric hydroxide. 



If much glycerin is present in the residue it may be 

 recognised by its physical characters. 



[In the case of palmitin, one of the constituents of 

 palm oil, the changes would be represented by the follow- 

 ing equations, which may be considered typical for 

 vegetable oils and fats. 



Palmitin (glyceryl tripalmitate) = C 3 H 5 (Ci 6 H 31 O 2 ) 3 



Pot. palmitate (soluble in water). 

 C 3 H 5 (C 16 H 31 2 )3 + 3KOH = 3C 16 H 31 2 K + C 3 H 5 (OH), 

 C 16 H 31 2 K + HC1 = C 16 H 31 8 H + KC1. 



Palmitic acid (insoluble in water). 



If saponification does not take place easily with 

 aqueous potash, alcoholic potash may be substituted, 

 and the heating must be done under a reflux condenser : 

 in this case the alcohol must be distilled off before 

 acidifying with hydrochloric acid.] 



Quantitative examination. 



Determination of total oils and fats. 



Proceed as in qualitative examination, but weigh the 



