fore the mine engineering class of the
Pennsylvania State College, Quoted by F. W. Gray, The conservation of
coal: _Bull. 47_, _Can. Mining Inst._, 1916, p. 201.

[49] _Loc. cit._

[50] Campbell, M. R., and Parker, E. W., Coal fields of the United
States, Papers on the conservation of mineral resources: _Bull. 394, U.
S. Geol. Survey_, 1909, p. 12.

[51] _Loc. cit._ p. 12.

[52] Smith, George Otis, and Lesher, C. E., The cost of coal: _Science_,
vol. 44, 1916, p. 768.

[53] _Loc cit._, pp. 768-769.

[54] _Loc. cit._, p. 771.

[55] Van Hise, Charles R., _Cooperation in industry_, pp. 7-8, Address
given before annual meeting of the National Lumber Manufacturers'
Association, Chicago, Illinois, May 31, 1916.

[56] _Loc. cit._, p. 767.

[57] Stabilization of the bituminous coal industry, Extracts from the
award and recommendations of the United States Bituminous Coal
Commission, Government Printing Office, Washington, 1920.

CHAPTER XVIII

INTERNATIONAL ASPECTS OF MINERAL RESOURCES

WORLD MOVEMENT OF MINERALS

Of the annual world production of minerals about two-thirds are used
within the countries where the minerals are produced and one-third is
shipped to other countries. In this chapter we are concerned primarily
with the part which moves between countries. It may be assumed that the
consumption within the countries of origin is a matter of national
rather than international concern.

In pre-war times minerals constituted about 33 per cent[58] of the value
of the total foreign trade of the United States, and 28 per cent of the
foreign trade of Germany. Figures are not available to show the
proportion of mineral tonnage to that of other commodities.

One of the several interesting facts in this world movement of minerals
is that the movement of most of them shows a rather remarkable
concentration. For instance, manganese moves from three principal
sources to four or five consuming centers. Chromite moves from two
principal sources; tungsten also from two. Even for certain commodities
which are widely distributed and move in large amounts, the
concentration of movement is rather marked; for instance, the world
movement of coal is controlled by England, the United States, and
Germany. In other words, although the world movement of mineral
commodities is widespread and exhibits many complex features, most of
the individual minerals follow two or three salient lines of movement.
This means in gene