41 
of the more recent stratified formations, of a predominating 
brown colour, in which the organic structure is usually dis¬ 
tinctly apparent. Some of these resemble peat, others 
consist of stems of wood (Fig. 13), leaves of trees or fruits 
(Fig. 12), half converted into coal; others, again, like 
needle-coal of Lobsann, in Elsass (Fig. 11), are evidently 
woody and vascular bundles of palm-stems converted into 
coal. In many districts, as, for example, Saulzhausen, in 
the Wetterau, whole series of fossil leaves and fruits are 
met with, and enclose freshwater fish; others have mosses, 
insects, etc. Stems, leaves, and cones of firs and pines are 
found in great abundance at Uznach, on Lake Zurich, and 
at Kapfnach carbonised teeth and bones of the rhinoceros 
(B. incisivus) have been found. Woody-fibrous brown- 
coal, the so-called lignite , is the most abundant. It is formed 
partly of pines and partly of other trees. The name of clay- 
coal has been given to a slaty, slightly lustrous coal, mixed 
with bituminous clay, which occurs in the lower keuper, 
in Swabia. It is interesting chiefly as often containing 
fossil ferns and calamites, fresh-water shells ( anodonta), 
and reptiles, and it is frequently so penetrated by pyrites 
as to give off green vitriol and alum on decomposition. 
Paper-coal is a finely foliated, flexible brown-coal, some¬ 
times not unlike brown pasteboard, easily set on fire, and 
combustible. It is found among the other brown-coals at 
>onn on the Bhine. Moor-coal is the name of a compact, 
lightly-lustrous variety of brown-coal, of low specific gra¬ 
vity, in which organic structure can only be discovered by 
lie help of the microscope. It takes fire readily, and burns 
well. It is sometimes light-brown, resembling umber or 
brown earth, and is found especially at the Westerwald, in 
Moravia and Hesse. Earthy-coal and Cologne-umber are 
eat lhy-brown-coals, more or less mixed with clay ; the 
alter is dug in the Cologne district, and, when washed, 
worked into conical forms, and dried, it is brought into 
the market as a colouring material. 
Peat. 
Peat is a combustible substance of more recent origin, 
not unlike brown coal, which is frequently found in con¬ 
siderable quantity in the wet lands of different districts, 
and is often produced under our eyes. This is the case 
especially in such places as have a marshy soil, or are 
ontinually kept wet, and covered with a corresponding 
vegetation, or peat-bogs . A substratum of clay or of 
compact rock, impervious to water, and an inclination of 
the soil so slight as to afford no exit to the water, are the 
necessary conditions, and they are found in the low ground 
of the valleys and extensive plains, as well as on the ridges 
of many mountains. The plants which are favourable to 
formation of peat must have the peculiarity of dying off 
from below upwards, and of growing at the top; to these 
belong, for example, many sedges [parex ccespitosa,filiformis, 
chordorrliiza) , the cotton grasses ( Eriophorum vaginatum , 
capitatum, latifolium ), some willows [salix repens, rosmarini- 
folia), the mosses ( Sphagnum, polytrichum, etc.), and the 
like. The dead stems, roots, and leaves, are gradually 
changed under the influence of water into a mouldy-look¬ 
ing substance resembling brown coal, in which the cells 
and bundles of vessels of the plants comprising it can still 
be recognised. The places of their occurrence are called 
peat-bogs , and, according to the different localities, meadow 
or marsh peat, A Peat usually forms regular layers, which 
are sometimes separated by a layer of clay or sand, and, 
according to their age, may reach a thickness of from a 
few feet to fifty or more. Peat-bogs of this depth, and of 
great extent, are found sometimes in the plains of Northern 
Germany, and in the flat land of Upper Swabia and 
Bavaria. The bogs of Ireland are estimated to cover 
3,000,000 acres of land. Many of them bear witness to 
their ancient origin by including animal remains of the 
diluvial period, as, for instance, gigantic deers, ure-oxen, 
and various tortoises, etc., and are therefore called diluvial 
peat, while, on the other hand, the newly forming bogs 
enclose only remains of animals of the present period, and 
frequently, also, traces of human industry. To the geolo¬ 
gist peat is interesting in many ways, because it best 
explains the origin of brown, and common coal. It is also 
very valuable as fuel, and in many cases it can take the 
place of coal and wood. The ashes contain as little alka¬ 
line matter as that of the common and brown coal. The 
heat given out by turf is about one half that of coal. 
Attention has of late years been directed to the various 
chemical compounds which may be obtained from peat, 
and various plans for obtaining them proposed. In the 
great exhibition of 1851, no less than seventeen different 
compounds were exhibited as extracted by Stone’s process, 
among the more remarkable of which were, ammoniacal 
liquor, peatole, paraffine, sulphuretted peat-charcoal, chloro¬ 
form, and tar. 
XIY. HEAVY METALS, METALLIC MINERALS OR ORES. 
The heavy metals are distinguished from the lighter 
metals of the alkalis and earths, and from the metalloids, 
by their greater atomic weight (= 5—24), by their more 
ready conversion into a metallic condition, their opaque¬ 
ness and metallic lustre, hardness, etc., and by their lower 
affinity for oxygen. They are found either native or as 
alloys, that is, in combination with other metals, or minera¬ 
lised by sulphur, selenium, bromine, chlorine, or oxygen ; 
the combinations with the last mentioned are called oxides, 
and they have either the peculiarities of a base, or of an 
acid, or sometimes of the one, sometimes of the other, or 
of a neutral oxide. Combinations of metallic bases with 
metallic or other bases are also found. The metals are, 
in a general way, divided into noble and common metals ; 
and under noble are comprised such as have little 
affinity for oxygen, and give it off by simple heating, and 
for this reason are easily separated from their combina¬ 
tions, and retain their lustre in the atmosphere. To 
this class belong gold, platinum, silver, paladium rhodium, 
iridium, and ruthenium; others which have some of these 
peculiarities, such as mercury, nickel, and copper, have 
been called semi-noble . The common metals include all 
