MILK TESTING. 69 



sufficient for most cases of adulteration occurring in practice, and 

 not only for an answer to the question as to whether milk is 

 adulterated or not, so far as this can be answered, but also for the 

 determination of the nature of any of the above-mentioned adul- 

 terations. Adulteration by watering is most easily seen in the 

 values (s) and (r), since both these values in unadulterated milk of 

 the most different origin vary between far narrower limits than the 

 values (/) and (t), as has been already mentioned in 10. For this 

 reason the determination of the specific gravity of milk furnishes 

 the most important evidence for forming an opinion on it, not only 

 as a preliminary test, but also as a thoroughly reliable ground of 

 final judgment. 



If, for example, (s) equals 1-0319, and (/) equals 3-50 per cent, with 

 the aid of the table, the calculation is worked out as follows: 



For (t) the value in the tables is 1*2 x / for 3-5 to 4 '2, and the 

 value of 



2-665 101 - for 1-0319 to 8-238 8-24 therefore is 



8-240 

 4-200 

 =12*440 percent, and r = 12-44 - 3-50 = 8-94': 



while for (m), by the tables, we find the value of 



- for 1-0319 to 3-091 ; therefore 



12-440 

 3-091 



"9^349)12.440 (1-33 

 ~ 3-0910 

 2863 



If milk with properties of this kind has been watered so that (s) 

 equals 1-0248, (/) will be found to equal 272 per cent, (t) to equal 9*71 

 per cent, (r) to equal 6*99 per cent, and (m) to equal 1-33. 



If, in the case of creamed and watered milk, (s) equals 1 -0270 and (/) 

 equals 1-695 per cent, (t) would be found to equal 9'041, (r) to equal 

 7-346, and (m) to equal 1'41. 



By simply watering milk, the original values of (s), (/), (t\ and (r) 

 are diminished throughout; while, on the other hand, the original value 

 of (m) remains unchanged, because the actual ratio of the individual con- 

 stituents of the dry substance does not suffer alteration. 



By creaming, the original values of (s) and (m) are increased, and to a 

 lesser extent that of (r); but the original value of (/) is very considerably 

 lowered, and that also of (/), but to a somewhat lesser extent. 



