THE ANNUAL CONSUMPTION OF COAL IN THE GLASGOW MARKETS. 175 
order to determine the state of the question ia 
reference to the existence of a central fire, 
the author has collected all the observations 
that have hitherto been published on the tem- 
peratures, from the surface of the earth to the 
greatest depth that has been attained by man. 
From these it appears that, taking the mean of 
nineteen ovservatibns, there is an increase of 
1° F, for every 50 feet of descent. This is the 
evidence which many bring forward for the 
existence of a central fire. The author, how- 
ever, shews, that according to the observations 
of Mr. Moyle, made during a series of years 
in Cornwall, the high temperature of these 
mines continues only while they are work- 
ing. When they are abandoned they are soon 
filled with water, which remains stagnant, 
and the temperature gradually sinks, till it 
approaches that of the mean temperature of the 
place. 2. That the temperature of the earth is 
regulated entirely by the sun, for, the higher 
the sun is elevated above the horizon and the 
longer it continues above the horizon, the 
higher is the temperature. If the temperature 
increased I^ for every 50 feet, a descent of 12 
miles or a point by so much nearer the centre 
of the earth than the position of the equator, 
should afford a temperature, allowing for radi- 
ation, of 1200*^. Now, this ought to be the 
temperature of the poles, because they are l2 
miles nearer the earth’s centre than the 
equator. Their temperature is, however,— 13*^, 
and hence, this seems a fatal argument to the 
notion of a central fire. But, although the 
idea of a central fire is not supported by the 
facts with which we are acquainted, it is not 
unlikely that an internal fire exists, which 
gives origin to those vast volcanic regions and 
earthquakes which are continually altering 
the aspect of the earth’s surface. If we were 
to consider this fire as approaching nearer the 
surface in some places than in others^, we 
might have, perhaps, an explanation of the 
relative causes of volcanoes and earthquakes. 
The remainder of the geological portion is 
divided according to the formations, beginning 
at the surface. Many original observations 
are detailed, especially in reference to the 
geology of Scotland, where the occurrence 
of most remarkable alterations in the relative 
levels of the sea and land is minutely detailed. 
The Glasgow coal beds are accurately describ- 
ed, The annual consumption ofcoalinthe 
Glasgow markets, it is stated, amounts to 
870,000 tons. But one of the most curious 
facts detailed, is the discovery, by the author, 
of a bed of coal in basalt, near Dairy, in 
Ayrshire, 
This bed is 4 feet thick, and is situated some 
hundred feet below the summit of Beadlan- 
hill, which is elevated 903 feet above the sea. 
Its specific gravity is l-3l7. Colour brown ; 
it is very hard. Burns with a livelv flame, 
and leaves 25*77 per cent, of earthy matter. 
It contains vegetable impressions differing 
from any that have hitherto been described, 
as derived from the coal formation. They 
appear to he fucoides. The only other loca- 
lity, where it is believed, coal has been found 
in basalt, is at Fairhead, in Ireland, but no 
fossils have been observed in it. 
The latter part of the second volume, con- 
sisting of above 200 pages is devoted to rules 
for the analysis of mineral substances, 
including stony minerals, metallic alloys, and 
mineral salts. This portion of the work is 
worth the attention of geologists as well as 
mineralogists, as it must be obvious to every 
one, who casts his eye over the vague specu- 
lations of too many of our present geologists, 
that without the application of chemistry, 
mineralogy, and natural history, geology is 
but a name . — Records of General Science. 
EXAMINATION OF HAIR SALT, OR 
NATIVE SULPHATE OF ALUMINA 
AND IRON. 
By Robert D. Thomson, M. D. 
(Continued from page 122.J 
The rock on which the salt lies is a 
granular schistose quartzose rock of a green- 
ish-gray colour, with small silvery scales of 
mica, and is impregnated with the salt 
matter which covers partly the surface with 
flakes, and partly incrusts it. The flocky 
portion consists of bitter salt, the crust of 
alum, with a small quantity of bitter salt. 
The rock on which the river flows is a gra- 
nular gray quartz, with some small scales 
of mica. The roof of the cave consists of red 
conglomerate, in which rolled quartz occurs, 
and occasionally pyrites and oxide of iron. 
The neighbourhood is formed of hills 800 
feet high, which are intersected by deep 
vallies, and capped by limestone. This lime- 
stone contains small portions of carbonate 
of magnesia, with traces of manganese and 
iron. Fossil oyster, and muscle shells 
were observed on the upper part of the 
hill, between Uitenhage and Enon. 
Hence, it would appear to be a very 
recent tertiary formation. It is worthy 
of notice that the alum and bitter salt 
are formed separately, and that neither 
of them contain iron, although the oxide 
of that metal occurs abundantly in the 
conglomerate. The feather alum, ac- 
cording to Hofrath Stromeyer, is a new 
hitherto undescribed species of alum, in 
which the sulphate of alumina occurs in 
combination with sulphate of manganese and 
sulphate of magnesia. Hence, he 
terms it mangan -magnesia alum. Sulphate 
of manganese has never previously been 
detected in any species of alum. 
At Tschermig, in Bohemia, an ammonia- 
cal alum is found, which, according to Lam- 
padius and Gruner, consists of Alumina 
11.602 Ammonia 3721 Magnesia 0-115 
