380 



Effective Farming 



FIG. 158. Type of knife- 

 edge cream balance. 



bottles. If there are not enough samples, fill the unused cups 

 with test bottles of water. Turn the handle of the tester for four 



minutes at the speed indicated for 

 the machine in use. Add moderately 

 hot water to the bottle to bring the 

 fat up to the neck of the bottle. A 

 pipette is convenient for this. Clean, 

 soft water should be used. If the 

 water available contains much lime, 

 add to it a few drops of sulfuric acid 

 to neutralize the lime . After the water 

 is added, put the bottles back in the 

 machine and whirl them again for one minute. Add hot water 

 as before until the fat stands at about the 7 per cent mark in 



the neck of the bottle. Place 



the bottles in the machine 



again, whirl for one minute, and 



read the percentage of fat, as 



shown in Fig. 161. The tem- 

 perature of the sample when 



read should be about 140 F. 



To calculate the reading, sub- 

 tract the reading at a (Fig. 161) 



from that at b. A convenient 



way to determine the reading 



is to place the points of a pair 



of dividers at the top and the 



bottom of the fat-column (see 



Fig. 162) ; then, being careful 



to keep this same distance be- 

 and WaU, Test- tween the points, slide them 



ing Milk and down until tlle lower Qne j g at 



Its Products.) 



the zero mark, as shown by 



the dotted lines. The upper one will give the reading direct. 



The methods of testing cream, skim-milk, buttermilk, and 



FIG. 159. The 

 right way of 

 adding milk to 

 the test bottle. 

 (Farr ington 



FIG. 160. The 

 wrong way of 

 adding the milk 

 to the test bot- 

 tle. (Farring- 

 ton and Wall, 

 Testing Milk 

 and Its Prod- 

 ucts.) 



