102 
that a prodigious development of a new and vigorous 
flora during both perioas—the spore-bearing fiora, in 
the main, of the Carboniferous, and the seed-bearing 
tlora of the Cretaceo-Tertiary period—was the chier 
contributory factor in the making of the world’s vast 
store of solid and liquid fuel. 1t contributed directly 
by supplying the vegetable matter for the coal, and 
indirectly by stimulating the development of a prolific 
plankton, from which the oil has been aistilled. 
The world’s production of petroleum has trebled 
itself within the iast 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 (includ- 
ing Egypt) produced only a little more than 2 per cent. 
In the near future Canada is likely to take its place 
as a great oil- and gas-producing country, for large 
areas in the Middle-West show promising indications of 
a greatly increased yield. But Mexico is undoubtedly 
the country of greatest potential output. Its Creta- 
ceous and Tertiary strata along the Gulf Coastal Plain 
are so rich that it has been stated recently on high 
authority that ‘‘a dozen wells in Mexico, if opened 
to their full capacity, could almost double the daily 
output of the world.”’? 
As is well known, natural supplies of petroleum are 
not found in the British Isles on a commercial scale; 
but for many years oil and other valuable products 
have been obtained from the destructive distillation 
of the Oil Shales of the Lothians. If Mr. Cunning- 
ham Craig is right in his views recently expressed,° 
these shales, or, rather, their associated freestones, have 
been nearer to being true petroliferous rocks than we 
thought; for he believes that the small yellow bodies, 
the so-called ‘‘spores’’ in the kerogen shales, are 
really small masses of inspissated petroleum, adsorbed 
from the porous and once petroliferous sandstones with 
which the shales are interstratified. 
If recent experiments on peat fulfil the promise they 
undoubtedly show, we shall have to take careful stock 
’ of the peat-bogs in these islands. It is well known 
that peat fuel has been manufactured in Europe for 
many years. But my attention has been called to a 
process for the extraction of fuel-oil from peat which 
has been tried experimentally in London, and is now 
about to be launched.on a commercial scale, utilisin 
our own peat deposits, like those of Lanarkshire an 
Yorkshire. 
The peat is submitted to low-temperature distillation 
at ordinary pressure, or at a slight negative pressure, 
the highest temperature reached: being about 600° C. 
From a ton of Lanarkshire peat, after the moisture 
is reduced to 25 per cent., 40 gallons of crude oil, 
18 to 20 lb, of ammonium sulphate, about the same 
quantity of paraffin wax, 30 to 33 per cent. of coke, 
and sooo to 6000 cubic ft. of combustible gas are ob- 
tained. The coke is said to be of very good quality. 
By the same process it is honed to get satisfactory 
results from the lignites of Bovey Tracey. 
Considering the rapid development of oil as fuel, and 
its supreme industrial importance in many other ways, 
it is remarkable that British geologists should have 
given such little attention to the origin and occurrence 
of petroleum. Among American. geologists a lively 
interest in this subiect has been aroused’ and a volu- 
minous technical literature is already published.’ And 
vet the fact remains that we are still in a cloud of 
uncertainty as to this vital question, upon the solution 
of which denends whether the prasnector of the future 
igs to work by hazard or on scientific and reasoned 
lines. 
Mr. Murray Stuart, now of the Indian ,Geological 
‘9 Ralph Arnold, “Conservat'on of the Oil and Gas Resources of the 
Americas,” Econ Geo/,. vo'. xi., No. 2, 1016, p 222. 
3 In titutioh of Petrolerm Technologicts, Apr'l, 1916. 
NO. 2440, vot. 98] 
NATURE 
[OcToBER 5, 1916 
Survey, offered in'1910* a simple explanation ot the 
occurrence of petroleum, basea upon iis own observa- 
tions in Burma, a research whicn seems to have at- 
tracted far more attention in America than in this 
country. He snowed that the oil ot the streams and 
swamps in Burma 1s carried down to the bottom of 
the water in small globules by adhering tiny particles 
of mud. Thus there is formed a deposit ot mud con- 
taining globules of oil and saturated with water. If 
afterwards this deposit is covered by a bed of sand, 
the oil and part of the water, as the pressure of over- 
lying sediment increases, are squeezed into the sand, 
so that by a repetition of the process a petroliferqus 
series of clays and sands may be accumulated. In 
examining lately a large quantity of the well-known 
“landscape marble” from the Rhetic of Bristol, I 
obtained from it small but appreciable amounts of 
petroleum; and towards the end of my investigation I 
was pleased to discover that I was in thorough agree- 
ment as to the origin of this curious landscape struc- 
ture with Mr. Beeby Thompson, whose research was 
published more than twenty years ago.* In these thin 
deposits of hydrocarbons among laminated silts, with 
their striking tree-like growths and hummocky surfaces, 
may we not have, in miniature, an illustration of the 
deposition and partial migration of netroleum which ~ 
occurs on so vast a scale in the oilfields of the world? 
It is not suggested that all petroleum deposits have 
had such an origin.. I am convinced, however, that in 
all geological ages such sedimentary accumulations 
have occurred; and that, excent where the conditions 
of cover have been favourable for its imprisonment, the 
oil is, and has been throughout geological time, in- 
cessantly escaping at the surface. Thus we may con- 
ceive the earth as continuously sweating out these stores 
of oil, either in the liquid or gaseous form, especially 
where rocks are being folded and rapidly denuded. 
It is sometimes asked whether the adoption of 
mineral oil as a power-producer is likely to supplant 
coal, and thereby seriously reduce the output of that 
mineral. The world’s yield of petroleum will doubt- 
less go on increasing at a very great rate; but from the 
experience gained in some of the fields in the United 
States and eastern Canada, it seems unlikely that this 
increase can continue for a very long period. Prac- 
tically complete exhaustion of the world’s supply is to 
be looked for within 100 years, says one authority.°® 
Even if the output rose to ten times the present vield, 
it would represent only about half the present world 
output of coal, and it is practically certain that so 
high a yield of oil could not be maintained for many 
years. Owing to the almost certain rapid increase in 
the output of coal, estimates made by the same 
authority indicate that the total production of petroleum 
could never reduce the world’s output of coal by more 
than about 6% per cent.” 
For us, and probably for those of the next genera- 
tion, the geology of petroleum will continue to be of 
immense practical importance; but coal will doubtless 
remain our great ultimate source of power. 
An obligation rests unon_us to see that the oil re- 
sources of the British Empire and of territories within 
our influence are explored. if possible by British 
reologists, with all the enecial knowledse that can be 
hrought to bear; and I am glad’ to think that the 
University of Rirminsham and the Imoerial College of 
Science and Technology, London, with this end in 
view, are doins pioneer work in giving a svstematic 
and snecialised training to our young petroleum 
technologists. 
4 “Rec, Geol. Surv. India,” 
mentary Denos‘t‘on of Oil.” 
_ 5 O.J.G.S., 1894 DD. 203-410. 
6 AS, Jevons, “British Coal Trade,” rers, p. 710. 
7 Thid., p. 716. 
vol. xl., 1910, pp. 320-33: “The Sedi- 
