SAMPLING. 209 



would furnish milk for sale. The taking of the latter class of 

 samples presents no difficulty ; the only precaution to be observed 

 is that the bottle into which the sample is poured is clean and 

 dry, and that it has a well-fitting cork. The proper sampling 

 of a large bulk of milk is by no means easy ; the bulk to be 

 sampled will be, in most cases, a churn, and the milk in these 

 should be mixed with a stirrer consisting of an iron rod carrying 

 a perforated tin plate ; the stirring is performed by working the 

 stirrer up and down. 



The " milk thief," a trough with a small opening in it, is also 

 employed. The milk to be sampled is made to pass along the 

 trough, and a little trickles out of the hole into a convenient 

 receptacle beneath. This method gives fairly representative 

 samples and requires no labour. 



Small quantities of milk may be mixed by pouring to and fro 

 from one vessel to another. 



The samples should then be taken by means of a dipper or, 

 better, by a sampling tube. This consists of a long tube open 

 at both ends, the lower being flat ; a flat plate is attached to a 

 rod which runs down the middle of the tube, so that by raising 

 the rod the plate can be pressed against the bottom of the tube 

 enabling it to contain liquid. To take the sample the tube is 

 lowered slowly into the churn, the plate being kept away from 

 the bottom to allow the milk to rise ; when the milk has com- 

 pletely filled the tube the rod should be raised, and the tube 

 withdrawn to prevent the exit of the milk ; the sample can then 

 be transferred to a convenient receptacle by placing it under the 

 tube and depressing the rod. 



Another method of sampling bulks of milk, which is scarcely 

 less exact than the preceding, is to tip the contents of the churn 

 into a strainer with sides, the slope of which causes the milk to 

 be thrown from side to side at an angle of 45°. The milk finds 

 an exit through the wire gauze at the sides of a circular well, 

 which should dip into a small tank of such size that the milk 

 rises to the top of the wire gauze ; a hood at the back prevents 

 spilling and facilitates mixing. The sample should be taken 

 from the tank with a dipper or sampling tube. This method of 

 sampling has the advantage of removing any particles of straw, 

 dust of food, etc., that may be found in the milk. If the tank be 

 provided with a tap the milk can then be run off. 



A convenient method of taking a composite sample of aU the 

 churns received from one farm is by the use of a large tin pot 

 provided with a spout, which extends from top to bottom, 

 :ind which communicates with the pot throughout its whole 

 length by a series of holes ^ inch diameter, about J inch 

 apart. The samples from each churn are emptied into the pot, 



U 



