is a good
record for a cow to make. Some cows yield as high as five or six per
cent but they do not generally keep up this record all the year.

[Illustration: FIG. 274. BABCOCK TESTER AND HOW TO USE IT
The tester, acid, acid measure, test-bottle, and thermometer at bottom;
filling the pipette on right; adding the acid and measuring the fat at
top]

The Babcock tester shows only the amount of pure butter-fat in the milk.
It does not tell the exact amount of finished butter which is made from
100 pounds of milk. This is because butter contains a few other things
in addition to pure butter-fat. Finished and salted butter weighs on an
average about one sixth more than the fat shown by the tester. Hence to
get the exact amount of butter in every 100 pounds of milk, you will
have to add one sixth to the record shown by the tester. Suppose, for
example, you took one sample from 600 pounds of milk and that your test
showed 4 per cent of fat in every 100 pounds of milk. Then, as you had
600 pounds of milk, you would have 24 pounds of butter-fat. This fat,
after it has been salted and after it has absorbed moisture as butter
does, will gain one sixth in weight. As one sixth of 24 is 4, this new 4
pounds must be added to the weight of the butter-fat. Hence the 600
pounds of milk would produce about 28 pounds of butter.

EXERCISE

1. Find the number of pounds of butter in 1200 pounds of milk that
tests 3 per cent of butter-fat.

2. A cow yields 4800 pounds of milk in a year. Her milk tests 4 per
cent of butter-fat. Find the total amount of butter-fat she yields.
Find also the total amount of butter.

3. The milk of two cows was tested: one yielded in a year 6000
pounds of milk that tested 3 per cent of fat; the other yielded
5000 pounds that tested 4 per cent. Which cow yielded the more
butter-fat? What was the money value of the butter produced by each
if butter-fat is worth twenty-five cents a pound?

CHAPTER XII

MISCELLANEOUS

SECTION LXIV. GROWING FEED STUFFS ON THE FARM

Economy in raising live stock demands the production of all "roughness"
or roughage materials on the farm. By roughness, or roughage, of course
you understand that bulky food, like hay, grass, clover, stover, etc.,
is meant. It is possible to purchase all roughage materials and yet make
a financial success of growing farm animals, but this certainly is not
the surest way to succeed.