TESTING BUTTER 637 



The 6 inch, 6 gram, 90 per cent bottle. The graduated portion, 

 of the bottle has a capacity of 90 per cent of the sample tested. 90. 

 per cent of 6 grams = 5.4 grams. Since the specific gravity of 

 butterfat, under test conditions, averages approximately .9, the 5.4 



5 4 

 grams of butterfat occupy a space of ~ or 6 cc. The volume of 



the neck of the test bottle, from to 90, therefore, must be exactly 

 6 cc. This volume calls for a type of "bottle with the following 

 dimensions : Height over all, approximately 6.5 inches. Length of 

 graduated portion of neck, 93.5 mm. Diameter of graduated por- 

 tion of neck, 9.04 mm. The graduation from to 90 is divided into 

 90 divisions. This bottle is adapted for Babcock testers with a 

 diameter of less than 18 inches. 



Scales, sensibility reciprocal .01 grams. 



Chemicals, commercial sulphuric acid, specific gravity 1.82 to 

 1.83. Glymol, or high grade white mineral oil. 



Operation of Test with 9 inch, 9 gram, 90 per cent bottle.- 

 Transfer, preferably by pouring, 9 grams of the properly prepared, 

 thickly fluid sample of butter into the test bottle previously balanced 

 on the scales. Add 9 cc. of lukewarm water and then 17.5 cc. com- 

 mercial sulphuric acid. Add the acid carefully, in small portions, 

 mixing thoroughly after each addition, until all of the 17.5 cc. has 

 been added. This precaution is necessary in order to avoid exces- 

 sive foaming and loss of sample due to action between acid and salt 

 in the butter. 



After the contents of the bottle have been thoroughly mixed, add 

 a sufficient amount of water to fill the bottle to the base of the neck. 

 Centrifuge in Babcock tester for five minutes at the usual speed for 

 the same size tester as used for milk and cream. See Table 104. Add 

 hot water to near the top of the graduation and whirl for four min- 

 utes. Transfer bottles to the hot water bath and hold at a tem- 

 perature of 125 to 130 F. for not less than three minutes. Add a 

 few drops of glymol and read at once. The reading gives the per- 

 centage of butterfat direct. 



Operation of Test with the 6 inch, 6 gram, 90 per cent bottle. 

 Follow the directions given for the operation of the test with the 

 9 inch, 9 gram, 90 per cent bottle with the following modifications : 

 Instead of 9 grams, weigh 6 grams of the butter into the test bottle, 



