80 Testing Milk and Its Products. 



per cent, are sufficiently exact for most commercial pur- 

 poses, e. g., in creameries, and this form of cream bottle 

 will be found very convenient in making tests of composite 

 samples of cream. 



92. Use of milk test bottle. Cream may be tested by 

 emptying a 17.6 cc. pipetteful of the sample into two or 

 more milk test bottles, dividing the amount about equally 

 between the bottles and filling the pipette with water once 

 or twice, which is then in turn divided about equally 

 between the test bottles; the per cent, of fat in the cream 

 is found by adding the readings obtained in each of the 

 bottles. Milk and water must be mixed before the acid 

 is added. 



This method does away with the error incident to the 

 adhesion of cream to the side of the pipette, but not that 

 due to the low specific gravity of the cream, and the re- 

 sults obtained will therefore be too low. The dilution of 

 the cream with water in the test bottles not only makes 

 it possible to bring into the bottle all the cream measured 

 out, but also insures a clear test. If ordinary cream is 

 mixed with the usual quantity of sulfuric acid used in 

 the Babcock test, a dark-colored fat will generally be 

 obtained, while the cream diluted with an equal or twice 

 its volume of water, when mixed with the ordinary 

 amount of acid, will give a light yellow, clear column of 

 fat, which will allow of a very distinct and sharp read- 

 ing. 



The number of bottles to be used -for testing a sample 

 of cream by this method must be regulated by the rich- 

 ness of the cream. If the sample probably contains 20 

 per cent, or more, a pipetteful should be divided nearly 



