The mineral industry of the British Empire and foreign countries : statistical summary (production, imports and exports) 1929-1931

Throughout the trade statistics in this document, materials
imported or exported on government account have been included as
far as possible.
Trade statistics for the United Kingdom include the trade
of Great Britain and Northern Ireland with the Irish Free State, and
exclude the direct foreign trade of the Irish Free State, which is
given separately.
Export statistics for Germany include deliveries on reparations
account.
Trade statistics for Japan do not include trade between
that country and the rest of the Japanese Empire. Trade figures
for Korea and Formosa include the trade with all other parts of the
Japanese Empire.
Production statistics in the case of Bavaria refer only to that
part of Bavaria lying to the east of the Rhine.
The units of quantity adopted are the British statute cwt.
and ton of 112 lb. (avdp.) and 2,240 lb. (avdp.) respectively, the
imperial gallon and the metric carat. For precious metals the troy
ounce of 480 grains is used.