THE DETERMINATION OF ACETYL NUMBER. 



iO 



Ac(tyl X umber on On>i'n/jZ Product i2Ias-sachu-? 



Diglyeerida. 



ir.- 



r.- 



XiilE. 



For 



I »'^'- N-STbi. -s.'si. 



Dipahniun, 

 Dist^arin, 

 Dioleiii, . 



(CiiHr.COO)jCiH='OH: . 

 (CirHi^COO JC5H.-.OH , 



ot.N 544 157 374 

 624 605 irg S5S 

 620.576 1S0.S26 



« w7 JIOISSO 

 89 S39 .011133} 

 90.413 .011OS04 



Gravimetric Process.'" 



After acetylating, a gravimetric process for acetyl number may be 

 conducted in a manner similar to that for the quantitative determination 

 of insoluble fattj* acids, observing aU the precautions therein noted as to 

 ceresine, washing, dning, weighing, etc. 



This modification is apparently rather more difficult, tedious and sub- 

 ject to error than the saponification or volumetric process ^Massachusetts 

 method^ A certain amotmt of loss arises from the dehydration of free 

 fattA- acids by acetic anhydride during acet^^lation, and is difficult to 

 prevent, although of Uttle consequence where the amount of free acids is 

 relatively small. 



The acer\-l number va) is calculated from the increase in weight (i) by 

 the following formula : — 



42.016 



or 1335.39604 i 



In case only one hydroxy* compotmd of known molecular weight (m) 

 and number of hydroxyk (d) is present, its amotmt can be calculated 

 from the increase in weight (i) of the oil, fat or wax on acetylating. The 

 theoretical increase for a hydroxy compound is — 



42.016 d 



* This procKs hss cot r«oe:red su£c:«iit st-dy L:: this liborstory to warraat positive state- 

 ments, but is simiiar to the toetihxis described by Lewkosrcsoh .^'o.' cilMi^', I, pp. SaS-SjS, 



4«6, 4e:. 



