II 



BUTTER 



'35 



If the sample of butter is to be examined chemically, it 

 should be melted by placing the bottle in water at 40 C. A 

 white layer, composed of the water from the butter along with 

 dissolved salts and casein, collects 

 at the bottom, and above it the 

 butter fat floats. On shaking vigor- 

 ously, the under layer can be again 

 incorporated with the fat, and this 

 must be done immediately before a 

 sample is taken. The condition of 

 emulsion of the brine is not altered 

 by the above-mentioned separation 

 of the non-fatty substances. 



If a small portion of the white 

 deposit is examined under the 

 microscope, it is seen that the brine 

 is still in the form of enormous 

 quantities of minute drops of liquid, 

 completely separated from one an- 

 other. The melting of the butter 

 has therefore riot caused the drops 

 of brine to run together. 



When butter is melted at a higher 

 temperature, e.g., 50-60 C., the 

 aqueous layer separates so quickly 

 that it is difficult to take a sample 

 after shaking, for the mixture does 

 not remain homogeneous for suffici- 

 ently long. 



When butter is melted and the fat separated from the brine, 

 it gives the so-called " butter lard," which is characterised by 

 keeping good for a long time. The examination of it is carried 

 out in the same way as for ordinary butter. 



B. THE CHEMICAL ANALYSIS. 

 1. DETERMINATION OF THE WATER. 



In practice a determination of the percentage of water in 

 butter is, next to the proof of adulteration, the most important 

 factor, for from it a simple, convenient, and, for most purposes, 



FIG. 56. A Large and a Small 

 Butter Sampler. 



