98 Testing Milk and Its Products. 



test bottle and the curd is shaken up with it so as to 

 wash out more of the sugar. Three cc. of acid are now 

 added as before and the test bottle whirled a second 

 time in the centrifuge. The whey is decanted again 

 and this second washing removes so much of the sugar 

 that what remains will not interfere with testing in the 

 usual way. The curd remaining in the bottle after the 

 second washing is shaken up with ten cc. of water; the 

 water-emulsion of the curd is then cooled ; the usual 

 amount, 17.5 cc., of sulfuric acid is added, and the test 

 completed in the same way as when milk is tested. The 

 amount of fat obtained in the neck of the test bottle is 

 calculated to the weight of condensed milk taken. 1 



108. Ice cream. Methods for determining the per 

 cent, of fat in ice cream have recently been worked out 

 by Holm 2 and Howard. 3 The former recommends the 

 use of a mixture of equal parts of hydrochloric and 

 glacial acetic acid, in the place of sulfuric acid, as the 

 latter is likely to char the sugar in the ice cream, thus 

 giving difficulty in reading the results. Nine grams of 

 the sample are weighed into a Babccck milk bottle, 

 which is then filled almost to the neck with the mixture 

 of the two acids given. This is then heated for a few 

 minutes until black, when the bottle is whirled in the 

 tester and water added to bring the fat column within 

 the graduations of the neck, as in the regular Babcock 

 test. The reading multiplied by two gives the per cent, 

 of fat in the ice cream. 



1 The Gottlieb method gives very satisfactory results with both 

 cheese and condensed milk (see 2f>i). 



2 Report Dept. of Health, City of Chicago, 1006, p. 50. 



3 Journ. Am. Ohem. Soc., 1907, p. 16. 



