40 million cakes of soap, and fertilizer for 3 million bushels of
wheat. On the other hand, 300 cities produced 52 million pounds of
pork by feeding their garbage to hogs.

The Department of Agriculture has shown that the waste of a half-
cup of milk daily by each of the 20 million families in the United
States would equal in a year the total production of 400 thousand
cows; that one ounce of meat or fat saved daily would in a year
mean 875 thousand steers, or a million hogs; and that if 81
percent of the whole wheat were used in bread instead of 75
percent, the saving in a year would feed 12 million people. During
the war our government organized a campaign for the salvage of
"junk," and the total amount collected had a value of 1 1/2
billion dollars. The school children of Des Moines, Iowa, are
reported to have gathered and sold two thousand dollars' worth of
waste paper in one week, and those of many other communities
obtained similar results.

VALUE OF BY-PRODUCTS

Every successful business man is constantly vigilant to discover
and remedy waste in his business--waste of materials, time, and
effort. Many of the most valuable products in certain industries
are "by-products,"--that is, products produced as an incident to
the main industry and from materials that otherwise would have
been wasted. In the manufacture of gas from coal, for example,
important by-products are coke, tar, and ammonia. There has been
great waste in the lumber industry, but now practically every
scrap from the tree may be used. In the Forestry Products
Laboratory at the University of Wisconsin, a process has been