650 ANNUAL, REPORT OF THE Off. Doc. 



water and this is run into the tubes in the same waj as the cream. 

 If three bottles are taken the pipette is filled with water a second 

 time and emptied into the bottles as before. This serves to rinse 

 the cream from the pipette, and at the same time to dilute it to a 

 point where it can be tested in the same way as milk. The bottles 

 are them treated in the usual manner, and the reading of the tubes 

 added together for the per cent, of fat in the cream. The neces- 

 sity of dividing the sample of cream as directed above may be 

 avoided by the use of the special test bottle shown in Figs. 18 and 

 19. Cream may also be tested in I he ordinary bottles by diluting 

 it with three times its volume of water and proceeding in exactly 

 the same manner as with milk, the reading being multiplied by 

 three. 



Owing to the low specific gravity of cream, the test sample, 

 if of the same volume, will weigh less than that of milk, and con- 

 sequently the per cent, of fat as shown by the scale will be less 

 than is found by gravimetric analysis, in proportion as the weight 

 is less than 18 grms. Where a delicate balance is available, this 

 error may be entirely avoided by weighing the cream used in a 

 test, and calculating the per cent, of fat by multiplying the scale 

 reading by 18, and dividing the product by the weight in grams of 

 cream taken. 



If 17.6 c. c. of cream are taken and the portion adhering to 

 the pipette is rinsed into the test bottle, a close approximation of 

 the true result may be obtained without weighing by correcting 

 the scale reading as follows: For a scale-reading of 20 per cent., 

 add 0.25 per cent.; for a scale-reading of 15 per cent., add 0.1 per 

 per cent. Readings between these may be corrected in proportion. 

 Below 10 per cent, oo correction is necessary. 



Cream may be tested in the ordinary bottles in the manner pro- 

 posed by Mr. Winton, in Bulletin 108, of the Connecticut Experi- 

 ment Station, by using a pipette having a capacity of 6.04 c. c, 

 which will deliver about 6 grams of average cream or one third 

 of the weight of the usual sample. When tbis pipette is used, 

 about 12 c. c. of water should be added to the cream in the bottle 

 before adding the acid. The usual amount of acid should be taken 

 and the test completed in exactly the same way as with milk. The 

 reading should be multiplied by three to obtain the per cent, of fat 

 in the cream. No correction for the specific gravity is necessary 

 when this pipette is used. 



86. Testing Skim-Milk, Buttermilk and Whey. 



With all products like the above, which usually contain less 

 than one per cent, of fat, more accurate results are obtained by the 



