state Dairy Association. 273 



the sides of the bottle instead of in the middle or instead of shak- 

 ing, either of which causes air bubbles to come in the milk which 

 will make the test lower than it should be. 



When the sample is thoroughly mixed, insert the pipette in 

 the sample and draw the pipette nearly full of milk, being careful 

 not to get milk into the mouth. Draw the pipette from the 

 mouth and quickly clap the first finger over the top. Then let 

 the milk run out gradually by lifting the finger slightly until it 

 falls in line with the 17.6 c. c. mark. Place the lower end of the 

 pipette in the test bottle as far as it will go and blow the milk into 

 the bottle, allowing it to drain out well. The sample is now ready 

 for the acid. 



ADDING THE ACID. 



The acid used should be commercial sulphuric, 1.82 specific 

 gravity, which can be purchased at any drug store. Great caro 

 should be taken in handling the acid, as it is very powerful and 

 quickly burns anything it touches. Its action can be counteracted 

 by cold water. The proper amount to add to the sample of milk 

 is 17.5 c. c. The acid measure is marked to contain this amount. 

 In adding it to the milk, pour it down the sides of the bottle's 

 neck slowly. Then mix with a rotary motion until the mixture is 

 a dark color. It will ordinarily take on a dark purplish hue. Then 

 let stand until all the samples are similarly prepared and place 

 them in the machine and make the first run of five minutes. Be 

 sure that the bottles are balanced in the machine. If there are 

 but three samples to run, put a bottle of water in the machine, 

 so as to make two bottles on a side, and preserve the balance. Keep 

 up the speed of the machine according to directions given on the 

 handle. 



After the first run of five minutes add water nearly boiling 

 hot to the bottom of the necks of the bottles and make a second 

 run in the machine of two minutes. Then add hot water, the same, 

 as before so as to bring the butter fat into the necks of the test 

 bottles so that the top line is not above the 8 per cent or 10 per cent 

 mark and the lower line is not below the mark. Run one minute. 



READING. 



Then read immediately. Do not let the tests stand for even 

 a few minutes, for the fat will contract and the test will be less, 

 accordingly. The number opposite the lower point of the butter 



A— 18 



