A DAIRY LABORATORY GUIDE 9 



with a knife as fine as possible in order to make it 

 possible for the acid to dissolve all of the casein. 

 After the cheese is weighed into the bottle, about 

 5 cc. of hot water are added and the mixture shaken 

 vigorously for two or three minutes. This softens 

 the casein. Enough warm water is then added to 

 bring the sample to approximately i8 grams. . The 

 sample is again shaken for two or three minutes, 

 and the ordinary amount of H2SO4 is then added. 

 If the cheese is old and dry, 2 or 3 cc. of H2SO4 in 

 excess of the usual amount are sometimes necessary 

 to dissolve the casein. In mincing the cheese the 

 sample should not be allowed to dry out any more 

 than is absolutely necessary. 



In the cases of both the butter and the cheese, 

 the results obtained must be reduced to an 18-gram 

 basis, when an 18-gram bottle is used. This can be 

 done by dividing the per cent obtained by the num- 

 ber of grams used and multiply the quotient by 18. 



Whey is usually tested in whole milk bottles, 

 although it is best to test it in skimmed milk bot- 

 tles when possible. The right bottle to use can 

 only be determined by actual experiment. Whey 

 requires less acid than whole milk, usually about 

 12 cc. 



