REICHERT-WOLLXV-POLEXSKE PBOCESS. 319 



solution of phenolptthalein solution in 50 per cent, alcotol 



N 

 added, and the solution titrated with j- baryta solution. To 



the figure thus obtained one-tenth is added, and the amount 

 found by a blank experiment subtracted ; the blank should not 

 exceed 0"33 c.c. 



In order to render this method more sensitive, if possible, for 

 the detection of small quantities of butter in margarine, Hehner 

 proposed the use of 5 c.c. only of alcohol, saponifying (almost 

 instantaneously) in a closed flask, warming for five minutes with 

 occasional shaking, and driving off the alcohol through a narrow 

 tube in a cork, reduced pressure being applied towards the end, 

 and the addition of 100 c.c. of water which has boiled at least 

 half an hour. He finds the blank figure thus to be less than 

 0"1 c.c, and the same as that given by 100 c.c. of boiled water 

 filtered through a dry filter ; other fats and oils give less than 

 0'06 c.c, and no increase is observed in heating them on the 

 water-bath with soda solution for two hours. 



To facilitate the melting of the fatty acids, tlie author proposes 

 lengthening the bulb tube, used by Wollny for distUlatiou, above 

 the bulb to 15 cm. and placing on it a small condenser, through 

 which water is kept running during the melting of the acids, 

 this being removed during distillation ; the same results are 

 obtained by the use of this apparatus as by ^\'ollny's. 



The Polenske Process. — For the detection of coco-nut 

 oil in butter, Polenske has drawn up very careful directions 

 for the carrying out of the Reichert- Wollny method, and his 

 process includes a determination of the volatile insoluble acids 

 in addition to the estimation of the volatile soluble acids. Alcohol 

 must not be used for the saponification, and glycerol, which was 

 first introduced by Lefimann and Beam, is employed : in fact, 

 so far as the saponification is concerned the method is that of 

 Leffmann and Beam. 



Five grammes of butter fat are weighed into a 300 c.c. Jena 

 glass flask (Fig. 44), and 20 grammes of glycerol are added, the 

 weight of the glycerol being exact to 0"1 gramme ; 2 c.c. of 50 per 

 cent, caustic soda solution are added, and the saponification 

 carried out by heating over a naked flame ; at first a considerable 

 amount of frothing takes place, and on continued heating the 

 solution suddenly becomes clear, after which the flask should 

 be set aside to cool slightly, and 100 c.c. of well-boUed distilled 

 water added. A little ignited pumice, which has been powdered 

 and sifted through muslin (Harris recommends that 01 gramme 

 should be used), and 40 c.c. of sulphuric acid (25 c.c. per litre) 

 added, and the flask immediately connected by a bulb tube 

 to a condenser. The sulphuric acid solution should be of such 



