CONTROL OF MILK. 379 



The first and third samples should be taken by a foreman or 

 other responsible person, preferably in the presence of the man ; 

 the foreman should be responsible for their conveyance to the 

 laboratory. 



The second series should be taken by an intelligent and respons- 

 ible person, who should receive instructions to take samples at 

 irregular intervals, and to avoid any semblance of rotation, 

 in order that the man shall not be able to form an idea when 

 he may expect a visit. He may be, with advantage, mounted 

 on a bicycle if the area of delivery is large. 



The first and third series may be taken in sample cans, 

 while the second series may be taken in five-ounce bottles, 

 which have been found to hold sufficient milk for analysis, while 

 not being too large to be carried easily. A case holding a dozen 

 bottles should be provided for this purpose. 



The testing of these samples may be performed largely with a 

 lactometer ; in fact, it is in this work that the usefulness of the 

 lactometer is most appreciated. 



The specific gravity of the samples of series (2) and (3) should 

 be compared carefully with those of series (1), which will form a 

 standard by which the others may be judged. In all cases the 

 specific gravities must be corrected to 60 F. Three cases may 

 occur. 



1. The specific gravity of a sample of series (2) or (3) is equal 

 to the specific gravity of the corresponding samples of series (1). 

 In by far the greater number of cases this indicates that the 

 composition of the samples is identical. It is possible, however, 

 that the milk may have been skimmed, which would raise the 

 specific gravity, and then watered slightly, which would bring 

 the specific gravity back to the original degree. It is, however, 

 excessively unlikely that a milk carrier could perform this feat 

 with such accuracy as would be required, and an experienced 

 observer would have his suspicions aroused by the thin appear- 

 ance of the milk. It is also patent that a man adulterating milk 

 for the sake of profit, or with malice, would not confine himself 

 to one isolated occasion, but would do so habitually ; and only 

 a skilled scientist could remove cream habitually from milk, 

 and reduce its specific gravity to the original degree by watering. 

 For all practical purposes it may be taken that when the specific 

 gravities agree the milk has not been tampered with. 



2. The specific gravity of the sample of series (2) or (3) is 

 higher than the specific gravity of the corresponding sample 

 of series (1). This indicates that it contains less cream than 

 the original. 



3. The specific gravity of the sample of series (2) or (3) is 

 lower than the specific gravity of the corresponding sample 



