20 



acid. One of the points most frequently neglected and underestimated 

 is attention to temperatures. Sulphuric acid acts more strongly upon 

 milk that is at a high temperature, than upon milk at a lower tem- 

 perature; also the higher the temperature the more the fat will ex- 

 pand and the greater the reading will be. Adopt some constant tem- 

 peratures for each step of the work ; the following have been found 

 very satisfactory. About 60 degrees for the milk when the acid is 

 added, about 140 degrees for the water added to the test bottles, and 

 between 130 degrees and 140 degrees for the water mto which the 

 test bottles are set before a reading is taken. If you prefer different 

 temperatures from those suggested, adopt them, but do not neglect to. 

 adopt constant temperatures. 



It sometimes is an advantage to add the water to tne test bottles 

 at twice rather than all at once, filling each bottle just to the neck at first, 

 and to about the eight per cent, mark the second time. Whirl the 

 tester for a minute after each addition of w.ater. 



9. Cost of testing composite samples : In a gallon of sulphuric 

 acid there is enough for about 260 tests. Estimating the value of the 

 acid to be 3ic. per pound, the cost of the acid for a single test would 

 be one-quarter of a cent. 



To find the average test of a number of samples : If the weights 

 and tests of a number of different lots are fairly uniform, the average 

 weight and test may be found by dividing the sum of the weights and 

 tests by the number of lots, but when there is no uniformity in the dif- 

 ferent lots, the true average test can be obtained only by multiplying 

 the total pounds of fat by 100 and dividing the product by the total 

 pounds of milk. There is sometimes a wide difference between the 

 mathematical average and the true average test of different lots. 



Testing Cream. 



The need of an accurate, simple, and speedy method of determin 

 ing the butter value of cream has become more and more urgent with 

 the general adoption of the Cream Collecting System of Creamery 

 management. 



The Oil Test has been used for many years with a measure of 

 success, but it may no longer be regarded as a reliable test for creamery 

 work. 



Its chief weak points and objections are as follows : 



1. The readings or tests vary with the churnability of the samples. 

 For example, a sweet sample, low in fat, will rarely yield an exhaus- 

 tive separation of clear oil or fat. A low rekding or poor test is usual- 

 ly obtained from such a sample. 



2. The amount of labor involved in properly caring for the tests. 



3. The machines used for the churning process are usually very 

 noisy and often troublesome. 



The B.abcock test for cream has stood the test of several years' 

 criticism and experience, and m.ay be regarded as a simple, accurate, 

 and satisfactory test for creamery work. 



