96 MILK PRODTTCTS 



watery solution with fuller's earth and filter- 

 ing. The filtrate is notably paler if caramel is 

 present. Fuller's earth differs in efficiency, and 

 each sample should be tested on known solutions. 



Preservatives. — The preservatives used in milk 

 may be found in limited amount in butter, but a 

 mixture of boric acid and borax is often added as 

 a substitute for salt. 



Glucose is sometimes used as a preservative, 

 especially in butter intended for export to tropical 

 countries. Crampton found as much as 10% 

 in a sample of highly colored butter intended 

 for exportation to Guadeloupe. For the de- 

 tection of glucose the phenylhydrazin test might 

 be used. For determination Crampton used the 

 following method: 10 grams of the sample were 

 washed with successive portions of convenient 

 bulk, the solution made up to 250 c.c, and an 

 aliquot portion determined, as given for lactose 

 on page 32. The solution may also be clarified 

 by alumina-cream or acid mercuric nitrate and 

 examined in the polarimeter. 



Boric Acid. — 2 5 grams of the sample are melted, 

 the watery portion separated and tested as de- 

 scribed on page 62, 



