BUTTER 59 



Butter (5 grams) yields a distillate requiring from 24 to 34 

 c.c. of decinormal alkali. Several instances have been pub- 

 lished in which genuine butter has given a figure as low as 

 22.5 c.c, but such results are uncommon. The materials 

 employed in the preparation of oleomargarin yield a distillate 

 requiring less than i c.c. of alkali. Commercial oleomargarin 

 is usually churned with milk in order to secure a butter flavor, 

 and, thus acquiring a small amount of butter-fat, yields dis- 

 tillates capable of neutralizing from i to 2 c.c. of alkali. 



If coconut oil has been used in the preparation of the oleo- 

 margarin, the figure will be higher, but there will still be no 

 difficulty in distinguishing pure butter. 



The determina,tion of the Reichert number will usually give 

 sufficient information as to the nature of a butter sample. In 

 doubtful cases it may be of advantage to apply other tests as 

 corroborative evidence. 



Saponification Value. — In the absence of coconut oil, the 

 saponification value will give valuable indications as to the 

 purity of a butter sample. It is possible to make oleomar- 

 garin, by the addition of coconut oil, which would have the 

 same saponification value as pure butter. 



Specific Gravity. — ^According to Skalweit, the greatest dif- 

 erences between the specific gravity of butter and its adulter- 

 ants are found at a temperature of 35°, but the determina- 

 tion is more conveniently made at the temperature of boiling 

 water. The Sprengel tube or Westphal balance may be em- 

 ployed for the purpose. 



Index of Refraction. — This datum differs notably in dif- 

 ferent oils, but it is not of much value in detecting adulteration 

 unless considerable of the adulterant be present. Several in- 

 struments have been devised for making refraction determina- 

 tion; the familiar ones are the refractometer of Abbe and the 

 butyrorefractometer of Zeiss. 



The butyrorefractometer has been strongly recommended for 



