ADULTERATION OF MILK.

The legal standards adopted in the different States of the Union determine the limits for fat or solids, below which the milk offered for sale must not fall. Where no control sample can be taken of a suspected sample of milk, calculations of the extent of the adulteration practised are made on basis of the legal standard in each State. Whenever possible, a control sample should be secured on the premises of the suspected party, and subjected to analysis. If the control sample contains appreciably less fat or solids not fat than did the suspected sample, the latter was skimmed or watered, or both skimmed and watered.*

SKIMMING.-I. If a sample is skimmed, the following formula will give the number of pounds of fat abstracted from 100 lbs. of milk:

Fat abstracted = x = legal standard for fat -ƒ,. (I)

f being the per cent of fat in the suspected sample.

In this and following formulas the percentages found in the control samples, if such are at hand, are always to be substituted for the legal standards.

II. The following formula will give the per cent of fat abstracted, calculated on the total quantity of fat originally found in the milk:

x = 100

f X 100
leg. stand. for fat

(II)

WATERING.-I. If a sample is watered, the calculations are most conveniently based on the percentage of solids not fat in the milk:

s being the per cent of solids not fat in the suspected sample.

Example.-A sample contains 8.5 per cent of solids not fat; if the legal standard for solids not fat be 9 per cent, 8.5 X 100 9

100

5.6, will give the per cent of extraneous

water in the suspected sample of milk.

*See Farrington-Woll, Testing Milk and its Products, 6th Ed., pp.

6-103.

= 5.6, will give the per cent of extraneous

water in the suspected sample of milk.

II. Watering of milk may also be expressed in per cent of water added to the original milk, by formula IV:

of water was added to the original milk.

WATERING AND SKIMMING.-If a sample has been both watered and skimmed, the extent of watering is ascertained by means of formula III; and the fat abstracted found ac cording to the following formula:

Example.-A sample of milk contains 2.4 per cent of fat and 8.1 per cent solids not fat; then

100 lbs. of the milk contained 10 lbs. of extraneous water and .33 lb. of fat had been skimmed from it.

RANGES OF THE VARIATIONS IN THE COMPOSITION OF HERD MILK. (FLEISCHMANN.)

The specific gravity (expressed in degrees) may go above or below the yearly average by more than 10 per cent. The per cent of fat may go above or below the yearly average by more than 30 per cent.

The per cent of total solids may go above or below the yearly average by more than 14 per cent.

The per cent of solids not fat may go above or below the yearly average by more than 10 per cent.