CH. XI] FATS. 245 



(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). 



C3H5 (Ci6H3i02)3 



Pot. palmitate (soluble in water). 

 C3H, (QeH3,0,)s + 3K0H = SCieHaiO^K + C3H„ (OH), 

 C,eH3xO,K + HCl = Ci3H3iO,H + KCl. 



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 acidi- 

 fying with hydrochloric acid.] 



Quantitative examination. 



Determination of total oils and fats. 



Proceed as in qualitative examination, but weigh the 



