MILK 



and 34, the way in which they work being easily seen from the 

 sketches. 



(3) Wooden stand to hold the bottles. 



(4) Water-bath of tin, with lamp; 

 for heating the test-bottles (see Fig. 

 35). 



(5) Centrifuge for whirling the 

 samples. Such centrifuges are made 

 in several forms, and are driven by 

 hand, steam, or electricity, and some 

 have an arrangement for heating 

 whilst in motion (see Fig. 36). 



(6) Commercially-pure sulphuric 

 acid of a specific gravity of T825 at 

 15 C. 



(7) Amyl alcohol. The properties 

 of this exercise a considerable influ- 

 ence upon the result of the analysis. 

 It must be chemically pure, the specific 

 gravity O815 at 15 C., and the boiling 

 point 128-130 C. 1 



The determination of the fat is 

 made in the following manner : 



The test-bottles are put into the 

 mouths 



FIG. 34. Automatic Mea 

 surer of Sulphuric Acid. 



stand with the 

 uppermost; then, with the 

 pipette designed for the 

 purpose or with an auto- 

 matic measurer, 10 c.c. of 

 sulphuric acid are filled 

 into the test-bottle, care 

 being taken not to allow 

 any to come in contact with 

 the neck. The few drops 

 remaining in the tip of the 

 pipette should not be blown 

 out. Then 11 c.c. of milk 

 are measured with the pro- 

 per pipette and allowed to 



i The amyl alcohol is best obtained from the firm from which the apparatus 

 is purchased. 



FIG. 35. Water-bath for Gerber's 

 Method. 



