TESTS USED IN CHEESE-MAKING 439 



the reading becomes 29.5. This means that the spe- 

 cific gravity is 1.0295. If the temperature of the 

 milk were 55 F., the correction is subtracted and 

 the reading becomes 28.5, equal to specific gravity 

 1.0285. 



Babcock's formulas for solids and solids-not-fat. 

 The following formulas were devised by Dr. Bab- 

 cock: 



(1) Formula for determining solids-not-fat. Sol- 

 ids-not-fat=*4L-|-o.2f, in which L is the reading of 

 the Quevenne lactometer and f is the per cent of fat 

 in the milk. 



(2) Formula for determining solids in milk. 

 Total solids=j4L+i.2f. 



These formulas can be expressed in the form of 

 rules as follows: 



Rule i. To find the per cent of solids-not-fat in 

 milk, divide the reading of the Quevenne lactometer 

 by 4, and to the result add the number giving the per 

 cent of fat in the milk multiplied by 0.2. 



Rule 2. To find the per cent of solids in milk, di- 

 vide the Quevenne lactometer reading by 4, and to 

 the result add the number giving the per cent of fat 

 multiplied by 1.2. 



THE HOT-IRON TEST 



This test is used for the purpose of ascertaining 

 when to remove whey from curd and when to mill 

 curd. An iron of convenient size and length for hold- 

 ing, as a half-inch gas-pipe, is heated fairly hot at one 

 end. The iron is carefully wiped with a cloth until 

 it is clean and smooth. A handful of curd is then 

 taken and placed in dry cloth and squeezed by the 



