COMPOSITION OF BUTTER. 9 



from 8'4 to 28"6 per cent., and in fresh butter from 4-18 to 

 15--i3 per cent. Wanklyn gives in fifty samples of the butter 

 supplied to the London workhouses in 1871, the water rang- 

 ing from 8-6 to 2 3 '7 per cent. "We have met, in one case, 

 with the extraordinary amount of 42'3 per cent. Bell found 

 the water to fluctuate between 4 '15 and 20 '75 per cent. 



Several methods may be adopted in order to produce an 

 excessively aqueous butter — either the milk is purposely left 

 in undue proportion during the process of manufacture, or it 

 is afterwards added by stirring the fused butter with water, 

 and cooUng the mixture very rapidly ; or lastly, the butter 

 and the water may be triturated together in the cold. Thus, 

 however, a product is obtained which is very light in colour 

 an J texture, enclosing a great number of air bubbles, which 

 at once characterise the mixture as adulterated. 



An unusually low percentage of water is likewise a 

 suspicious circumstance. If a butter containing the normal 

 amount of water be mixed with foreign fats containing no 

 water, a diminution of moisture wiU be the natural result. 

 Thus we have met with a sample, undoubtedly adulterated, 

 containing but 3"83 per cent., and we are by no means sure 

 that the low percentages of water found by several of the 

 observers above quoted, are not likewise due to the fact 

 that the butter was mixed with foreign fat. At the time the 

 analyses referred to, however, no method for detecting admix- 

 ture of foreign fats with butter was known. 



III. Casein, or Curd, is the nitrogenous matter of the 

 milk, some of which is invariably skimmed off with the 

 cream either in the coagulated state, or in solution, and 

 thence finds its way into the butter. Taking the average of 

 our analyses quoted in Chapter IL, we find that butter con- 

 tains about 2 '2 per cent., ranging from 1*1 to 5-1 per cent. 

 Hassall and Parkes give from 3 to 5 per cent. Casein, how- 

 ever, may be mixed with butter in much larger quantities, so 



