USE OF APPARATUS. 



To enable a manager to do full justice to his employers and 

 to milk suppliers he should, by preliminary practice in the use 

 of the graduated apparatus, make himself familiar with their 

 construction and thoroughly adept in their use. Not until such 

 time as he has acquired a complete command of the apparatus 

 and operations should he presume to decide authoritatively on 

 the milk supplied. The following short description of the con- 

 struction and use of the apparatus may be found helpful ; but 

 practice alone will give the needful dexterity and accuracy. 

 Useful practice may be obtained by repeated tests of the same 

 sample of milk. If without any failures he is able to secure 

 uniform results with one and the same sample he may proceed 

 with the official testing. 



i. PIPETTES. 



The correct method of handling the pipette is as follows : 

 Place the ball of the forefinger of the right hand on the upper 

 end of the pipette the finger being moist but not wet. Slide 

 the thumb and other fingers as far down the stem as possible. 

 In this way a firm and easy grip is ensured, and the slightest 

 easing of the pressure of the forefinger will allow the liquid to 

 flow out steadily. To fill, immerse the lower end of the pipette 

 well into the liquid, apply the mouth to the upper end and 

 draw up the milk until it stands slightly above the mark on 

 the stem. Then deftly replace the forefinger before the liquid 

 sinks. Some considerable practice may be necessary to enabla 

 the operator to control the flow of the milk from the pipette, and 

 to stop it when the liquid is at the mark. With clear liquids the 

 bottom of the dark curve or meniscus should be at the mark, 

 with opaque liquids, such as milk, the transparent edge of the 

 liquid should be just above the mark. 



In determining the position of the milk with relation to the 

 mark, hold the pipette in a vertical position, with the mark on 

 a level with the eye. In emptying the pipette keep it in a 

 vertical position, and give it a rotary motion by means of the 

 thumb and forefinger, so as to prevent any fine particles of fat 

 adhering. When empty touch the side of the receiving vessel 

 with the point of the pipette to get rid of the last drop. Do not 

 blow through the pipette. The small amount of milk which 

 remains in the point is allowed for by the maker in marking. 



ii. TEST BOTTLES. 



The neck of the test bottle is divided into ninety parts by lines 

 of varying length. To facilitate reading each tenth mark is 

 lengthened and each fifth mark slightly lengthened. In read- 

 ing, hold the bottle in a vertical position and in a good light. 



