150 Testing Milk and Its Products. 



sixth month from calving, in case of spring cows ; dur- 

 ing the third to fifth month in case of summer-calving 

 cows, and during the. fifth to seventh month for fall- 

 calving cows. 



In all cases composite samples of the milk for at least 

 two days should be taken (169). "The test of a single 

 sample, drawn from a single milking or day, will not of 

 necessity, or indeed usually, give trustworthy results." 

 b. As to quantity of milk produced. The milk may 

 be weighed for two days in the middle of the month, 

 and the entire month's yield obtained with considerable 

 accuracy (barring sickness and drying off), 

 by multiplying the sum by a factor, ac- 

 cording to the number of days in the dif- 

 ferent months. The weighing is read- 

 ily done by means of a spring balance, the 

 hand of which is set back so that the empty 

 pail brings it to zero (fig. 50). If several 

 pails are to be used, they should first be 

 made to weigh the same by putting a little 

 solder on the lighter pails. Milk scales 

 which weigh and automatically register the 

 yield of milk from twenty cows have been 

 Milk placed on the market, but so far as known 



have not proved satisfactory. 

 168. Sampling milk of single cows. In sampling 

 the milk of single cows, all the milk obtained at the 

 milking must be carefully mixed, by pouring it from 

 one vessel to another a few times, or stirring it thor- 

 oughly by means of a dipper moved up and down, as 

 well as horizontally, in the pail or can in which it is 



