304 MILK AND CREAM TESTING 



not to be recommended. The reasons for not favoring such are : 

 (1) The small capacity prolongs the time required to do a 

 moderate amount of work and greatly increases the likelihood 

 that the testing of the herd will not often be undertaken. (2) 

 The bottles are so thoroughly exposed to the air that unless the 

 bottle pockets are filled with hot water the contents cool too 

 rapidly to permit either of thorough testing or accurate reading. 

 (3) Test bottles do occasionally break^ and if such an accident 

 should occur in an open machine the chances are great that it 

 would at least cost the suit of clothes worn, and possibly cause 

 greater damage. 



A machine like that shown in figure 101 with a capacity of 

 eight to twelve bottles, enclosed with close-fitting cast-iron frame, 

 costs only ten to twelve dollars, with glassware complete. It pro- 

 tects the sample from being cooled in the air ; protects the oper- 

 ator from accident, and increases the likelihood of a good test. 



The glassware needed for the larger machine, constituting 

 one set, wiU consist of a dozen whole milk test bottles ; two or 

 more skim milk test bottles, and preferably, two cream test 

 bottles, two pipettes, graduated to 17.6 c.c. ; one pair needle- 

 point dividers ; and a few ordinary dishes for the pouring of 

 milk, and the handling of hot water. See figures 101, 102, 103, 

 and 104, for illustration of the various tools needed. 



Since glassware is liable to be broken and is not usually 

 carried in stock in villages, it is highly desirable that there be 

 procured at least two pipettes and acid measures, and a reason- 

 able stock of test bottles. Pipettes may be used to measure the 

 acid, but it is hard on the throat on account of the acid fumes. 



Properties of Milk. — Milk is a mixture of water in which is 

 dissolved a considerable quantity of milk sugar and a small 

 quantity of albumen, with casein, which is the chief substance 

 of which cheese is made, present in a fine suspension, and butter 

 fat which is present in the form of an infinite number of small 

 round globules. The composition of milk differs greatly between 

 breeds and individuals of the same breed. 



Although the protein (casein and albumen) and the ash are 

 far more important in the growing of calves, pigs and poultry 



