DETECTION OF RENOVATED BUTTER AND OLEO MARGARINE 659 



Moisture Determination 



(1). Weigh about one gram of properly prepared sample into 

 solids dish which has previously been treated as per directions for 

 Total Solids Determination of Fresh Milk, paragraphs 1 to 3, in- 

 clusive. 



(2). Heat solids dish with contents on hot plate at 180 C. 

 until foaming ceases. 



(3) Place in vacuum oven held at 100 C. for seven minutes. 



(4). Cool, weigh and calculate per cent moisture by dividing 

 loss in weight by net weight of original sample, and multiply quotient 

 by 100. 



Detection of Butter, Renovated Butter and Oleomargarine 



Microscopic Examination. Official. 1 "Place a small portion 

 of the fresh unmelted sample, taken from the inside of the mass, on 

 a slide, add a drop of pure sweet oil, cover with gentle pressure, and 

 examine with a one-half to one-eighth inch objective for crystals of 

 lard, etc. Examine the same specimen with polarized light and a 

 selenite plate without the use-of oil. Pure fresh butter will neither 

 show crystals nor a particolored field with selenite. Other fats 

 melted and cooled and mixed with butter will usually present crystals 

 and variegated colors with the selenite plate. 



For further microscopic study dissolve from 3 to 4 cc. of the fat 

 in 15 cc. of ether in a test tube. Close the tube with a loose plug of 

 cotton wool and allow to stand from twelve to twenty- four hours at 

 20 to 25 C. When crystals form at the bottom of the tube, they 

 are removed with a pipette, glass rod, or tube, placed on a slide, cov- 

 ered, and examined. The crystals formed by later deposits may be 

 examined in a similar way." 



Foam Test 2 



Heat a small piece of butter (2 to 3 grams) either in a spoon or 

 in an evaporating dish, over a free flame. Heat slowly until the fat 

 boils briskly. If it is butter it will boil quietly and noiselessly and 

 it will foam abundantly. If it is renovated butter or oleomargarine, 

 it will boil noisily, it will bump and sputter, like a mixture of hot 



1 Journal Association Official Agricultural Chemists, Vol. II, No. 3, 1916. 



2 Patrick, Household Tests for the Detection of Oleomargarine and Reno- 

 vated Butter, Farmers' Bulletin 131. 



