ch. s PLURALITY OF SECONDARY PRICE-LEVELS 71
Wheat .
100
112
104
97
Potatoes
100
186
157
188
Raw Sugar
100
86
89
Raw Cotton
100
101
100
101
Pig-iron .
100
91
75
Bituminous Coal
100
97
108
111
Petroleum
100
164
. .
141
Wool .
100
102
Hides
100
103
Coffee
100
248
172
A few of-these figures are probably erroneous and notstrictly comparable. In the case of potatoes, whichenter dubiously into international trade, the British figure may have been heavily influenced by transientcircumstances of crop or season. But the broadlessons of the table are evident. Raw materials, suchas cotton, wool and hides, which are not subjected totariffs, and travel easily, maintain their internationalparities very accurately. But the prices of manyother important commodities, such as wheat and pig-iron, are capable of sustaining a markedly discrepanttrend in different countries.
Nevertheless, when there are marked differencesbetween the movements of the Purchasing Power ofMoney within a country and those of its InternationalPrice-Level, this is likely to be a matter of import-ance for the interpretation of the monetary equilibriumand price movements of the locality. At the date atwhich I write this chapter (1927), one of the mostinteresting monetary phenomena of the day is thegeneral tendency for the International Price-Levels to
1 I.e. if the price of a commodity has risen 10 per cent in Great Britain within this period and 20 per cent in the United States, our index aboveshows 109 for the U.S. , i.e. 120/110.