Petroleum: Present and Future Prospects. 561 
wealth should be set aside to provide the means for the discovery and 
development in our Islands of new mineral fields ? 
Chemical and Microscopical Investigation of Coal-seams. 
. The recovery of bye-products in the coking of coal, which up to 
the beginning of the War was almost exclusively undertaken by the 
Germans, is likely in the future to become an important British | 
industry. This will ultimately demand a thorough knowledge of the 
microscopic and chemical str ucture of all the important coking seams 
in our coalfields. 
Remembering how varied both in microscopical structure ae 
chemical composition the individual laminz of many of the thick 
coal-seams are, it will readily appear how important such a detailed 
investigation may become, having regard to the great variety of 
these bye-products and their industrial application. Moreover, thin 
seams, hitherto discarded, may pay to be worked, as may also an 
enormous amount of small coal, estimated at from 10 to 20 per cent 
of the total output, which up to the present has been wasted. 
Geology of Petroleum. 
It has been frequently remarked that in order to account for the 
vast accumulation of coal in the Carboniferous strata, it is necessary 
to postulate a special coincidence over great areas of the Northern 
Hemisphere of favourable conditions of plant growth, climate, 
sedimentation, and crustal subsidence; conditions which, although 
they obtained at other geological periods over relatively small areas, 
were never repeated on so vast a scale. Having regard to the 
estimates of coal deposits in Cretaceous and Tertiary strata, published 
in our first International Coal Census, the ‘‘ Report on the Coal 
Resources of the World’’,! it would appear that we might reasonably 
link the Cretaceo-Tertiary Period with the Carboniferous in respect 
of these peculiar and widely prevalent coal-making conditions. For 
I find that of the actual and probable reserves of coal in the world, 
according to our present state of knowledge, about 43 million 
million tons of bituminous and anthracite coal ‘exist, the vast bulk 
of which is of Carboniferous age; while there are about 3 million 
million tons of lignites and sub-bituminous coals, mostly of Cretaceous 
and Tertiary age. 
When we look to the geological distribution of petroleum, we note 
that it is to be found in rocks of practically every age in more or 
less quantity, but that it occurs par excellence, and on a great 
commercial scale, in rocks of two geological periods (to a smaller 
extent in a third); and it is significant that these two periods are 
the great coal-making periods in geological history—the Carboniferous 
and the Cretaceo- Tertiary. . 
‘The world’s production of petroleum has trebled itself within the 
last fifteen years. In 1914 the United States of America produced 
66°36 per cent, and North and South America together nearly three- 
fourths of the world’s total yield; while the British Empire 
1 Report on ‘‘ The Coal Resources of the World’’, for the Twelfth Intern. 
Geol. Congress, 1913. 
DECADE VI.—VOL. IlI.—NO. XII. 36 
