TESTING 263 



.009 X 8 ^ 



— — X 100 = .4 per cent acid in the cream. This 



can be obtained quickly by dividing the amount of alkali 

 by the arbitrary number 2 and by reading the quotient 

 in tenths as follows ; 8 c.c. -h 2 = A per cent acid. If 9 

 grams, or only half of 18 grams, of cream were used, the 

 result would be obtained directly by reading each cubic 

 centimeter of alkali as .1 per cent. In this way, the 

 reading is rapid, with only a little mental calculation. 



GENERAL NOTES OF TESTING 



The most important factor in testing is accuracy. All 

 chemistry operations, of which testing dairy products is 

 one, demand carefulness. 



237. System. — One of the essential considerations 

 in running a test is system. All sample bottles should be 

 plainly labeled. When all the samples are obtained, each 

 should be arranged in consecutive order. Then the test- 

 bottles should be clearly marked and arranged in order. 

 When this is done, if a mistake is made, such as forgetting 

 to label a test-bottle, its position would be sufficient to 

 identify it. There should be a special place for the re- 

 cording of each test. A student in the laboratory can plan 

 for a systematic recording of the tests. It might be 

 possible for him to prepare his notebook when the cen- 

 trifuge is running. In a creamery there should be special 

 printed sheets for such records. The above suggestions 

 will aid in increasing the speed as well as the accuracy of 

 the testing operation. 



238. Conveniences for testing. — A few conveniences 

 might be used to increase the speed of testing, such as 

 the following : (1) A warming tank with a rack in which 

 to place samples that should be heated before being 



