194 SCIENCE AND PRACTICE OF DAIRYING. 



When properly manufactured, the raw butter from the churn, 

 after being passed through a hair sieve and before being worked, 

 contains about 16 to 22 per cent of water, and between 76 and 82 

 per cent of fat. In the preserved butter of commerce the quantity 

 of the individual constituents very rarely exceeds the limits of the 

 following percentages : 



Limits for the percentage of water, 7 to 16 percent. 



fat, 80 to 91 



Other organic constituents, ... ... ... '8 to 2 



Limits for the percentage of ash (not including ) , , . 



the salt added), J 



The best kinds of butter contain not less than 82 per cent of 

 fat, not more than 15 per cent of water, and not more than 2 per 

 cent of the other constituents, exclusive of the added salt. 



Pure butter is a bad nourishing medium for micro-organisms. 

 The more nitrogenous matter the butter contains, the more favour- 

 able is it for the growth of bacteria and moulds in and on the 

 butter. The keeping qualities of butter especially are in danger, 

 if decomposition bacteria have developed, during souring, in the 

 liquid churned, and infect the butter. 



The average chemical composition of the finished article is indicated 

 by the following analyses : 



From Sweet Cream and From Sour Liquid 



without Salting. Salted. 



Unwashed. Washed. Unwashed. Washed. 



Water, 15-00 15-00 12-00 12-50 



Fat, 83-47 8373 84-75 84-62 



Protein matter, 0-60 0-55 0*50 0*48 



Other organic matter, ... 0'80 0'60 0'55 0'40 



Ash or ash and salt, ... 0-13 0'12 2-20 2-00 



100-00 100-00 100-00 100-00 



The specific gravity at 15 C. is, on an average, -9437 for unsalted butter, 

 and -9515 for salted butter. The melting and solidifying point of butter 

 are approximately the same as those which were given in 6 for pure 

 butter fat. 



As an example of the chemical composition of the pure ash of butter, 

 the following results give the composition of the ash of unsalted, unwashed, 

 and well-worked butter made from sour cream : 



