386 Missouri Agricultural Report. 



form provided with a graduated stem, which enables the operator 

 to determine the depth to which the instrument sinks in milk. 

 Numbers registered on the lactometer scale range from 15 to 40. 

 These are called the lactometer degrees. If the lactometer sinks 

 to a depth of 31 on the scale, it means that the milk has a specific 

 gravity of 1.031. In normal milk the lactometer shows a specific 

 gravity of 1.029 to 1.034. Between each of the numbered divisions, 

 as 25 to 30, there are five subdivisions, which enable the operator 

 to read to a .001 on the specific gravity scale, or less, if care is 

 taken in the observations. 



There are other forms of lactometers in use, but the Que- 

 venne's is generally preferred because of its greater accuracy. A 

 lactometer should always be provided with a thermometer, in or- 

 der that the necessary corrections for temperature of the lacto- 

 meter readings may be made. 



INFLUENCE OF TEMPERATURE. 



Whenever a lactometer reading is made, the temperature of 

 the milk should also be recorded, because a variation of 10 degrees 

 in temperature affects the lactometer reading to the extent of 1 

 degree. When the milk is cold, it is contracted in volume, and the 

 lactometer does not sink to as great a depth as if the milk were 

 warm. This results in the lactometer recording a high specific 

 gravity. On the other hand, if the milk is too warm, it is ex- 

 panded, which has the effect of diluting the milk, causing the lac- 

 tometer to sink to a greater depth and a lower specific gravity 

 to be secured. In making corrections for temperature, the fol- 

 lowing general, rule can be applied : When the temperature is 

 greater than 60° F., add .1 of a lactometer degree for each degree 

 of temperature, and when less than 60° F., substract .1 for each 

 lactometer degree. This general rule will apply only for a varia- 

 tion of 10 degrees either above or below the temperature of 60°. 



INFLUENCE OF SKIMMING AND WATERING. 



Since milk has a specific gravity vorying from 1.029 to 1.034, 

 it follows, as previously stated, that any addition of water neces- 

 sarily lowers the specific gravity, and any removal of the fats neces- 

 sarily raises the specific gravity. When skimming alone or watering 

 has been practiced, it is easily detected by means of the lactometer ; 

 but when milk is both skimmed and watered, the lactometer results 

 fail to reveal the fact. The water lowers the gravity, and the re- 



