36 MODERN METHODS OF TESTING MILK 



exactly 2 cc. between the o and 10 marks. Since I cc. 

 of pure milk-fat is known to weigh .9 gram, 2 cc. of 

 milk-fat, the amount required to fill the neck between 

 the o and 10 marks, weighs 1.8 (.9x2) grams, which 

 amount is just 10 per cent, of the 18 grams of milk 

 sample used in testing. 



In the form shown in Fig. 7a, which is coming into 

 common use, the scale is limited to 8 per cent., while 

 the smallest divisions measure o.i per cent. (See 

 P- 275). 



The divisions on the neck of the test-bottle should be 

 accurate and uniform; the lines should run straight 

 across the neck and not obliquely. When the marks 

 and numbers become indistinct from use, they can 

 be rendered clear by rubbing the scale over with the 

 lead of a pencil or with a cloth having on it a little 

 printer's ink or black paint. When in use, each bottle 

 should be numbered or labeled in a distinctive way. 



MILK-MEASURING PIPETTE 



The form of pipette in common use is shown in Fig. 

 8. Other forms are shown in Figs. 9 and 10. The 

 pipette should hold 17.6 cc. when filled to the mark. 

 Since about .1 cc. of milk will adhere to the inside, 

 such a pipette will furnish a sample amounting to 

 17.5 cc. of milk, which weighs about 18 grams, I cc. 

 of milk weighing about 1.03 grams on an average. 

 The accuracy of the test, so far as regards the amount 

 of sample taken, depends upon the exactness of the pi- 

 pette in holding 17.6. The mark on the stem should, 

 for convenience, be two inches or more from the up- 



