The nodules from the "blue earth" have to be freed from matrix and divested of their opaque crust, which can be done in revolving barrels containing sand and water.
Beckerite, a rare amber in earthy-brown nodules, almost opaque, said to be related in properties to gutta-percha.
The nodules are penetrated by cracks,;but the material can be worked on the lathe.
The nodules, in particular, appear to play the important part in the process.
The nodules on the roots of leguminous plants are induced by the presence of a minute organism now known to do no injury to the plant.
Nodules due to eel-worms (Nematodes) are produced on numerous classes of plants, and frequently result in great losses-e.g.
The term coprolites has been made to include all kinds of phosphatic nodules employed as manures, such, for example, as those obtained from the Coralline and the Red Crag of Suffolk.
Thick, containing rolled fossil bones, cetacean and fish teeth, and shells of the Crag period, with nodules or pebbles of phosphatic matter derived from the London Clay, and often investing fossils from that formation.
These nodules were at first taken by Professor J.
"The nodules, having been imbued with phosphatic matter from their matrix in the London Clay, were dislodged," says Buckland, "by the waters of the seas of the first period, and accumulated by myriads at the bottom of those shallow seas where is now the coast of Suffolk.
The phosphatic nodules occurring throughout the Red Crag of Suffolk are regarded as derived from the Coralline Crag.
An acre used to yield on an average 300 tons of phosphatic nodules, value £750.
Phosphatic nodules occur also in the Chloritic Marl of the Isle of Wight and Dorsetshire, and at Wroughton, near Swindon.
Beds and nodules of chert are abundant in the upper parts of the limestone; at Bakewell it is quarried for use in the Potteries.
The existence of the root nodules had long been recognized, but hitherto no adequate explanation had been afforded as to their function.
Upon the roots of leguminous plants characteristic swollen nodules or tubercles are present.
The nodules increase in size, and analysis shows that they are exceedingly rich in nitrogen up to the time of flowering of the host plant.
East of the Great Fault (already mentioned) the beds are more regular, comprising, in descending order, (a) Upper Coralline Limestone; (b) Yellow, Black or Greensand; (c) Marl or Blue Clay; (d) White, Grey and Pale Yellow Sandstone; (e) Chocolate-coloured nodules with shells, &c.; (f) Yellow Sandstone; (g) Lower Crystalline Limestone.
Larger quantities of deposit may be conveniently collected by means of the dredge, which can be worked in any depth and brings up large stones, concretionary nodules or fossils, of the existence of which a sounding-tube could give no indication.
Secondary products, such as glauconite, phosphatic concretions and manganese nodules, occur though less frequently than in the hemipelagic sediments.
The dredge often brings up large numbers of nodules formed upon sharks' teeth, the ear-bones of whales or turtles or small fragments of pumice or other volcanic ejecta, and all more or less incrusted with manganese oxide until the nodules vary in size from that of a potato to that of a man's head.
The manganese nodules afford the most ample proof of the prodigious period of time which has elapsed since the formation of the red clay began; the sharks' teeth and whales' ear-bones which serve as nuclei belong in some cases to extinct species or even to forms derived from those familiar in the fossils from the seas of the Tertiary period.
In the Chalk of the south-east of England nodules of marcasite with a fibrous radiated structure are abundant, and in the Chalk Marl between Dover and Folkestone fine twinned groups of "spear pyrites" are common.
In whatever form they were originally deposited they often suffer complete or partial solution and are redeposited as concretionary lumps and nodules, often called coprolites.
Phosphatic nodules and concretions, with phosphatized fossils and their casts, occur at various geological horizons in Great Britain.
Bands of black nodules, highly phosphatic, are found at the top of the Bala limestone in North Wales; beds of concretions occur in the Jurassic series; and important deposits are known in the Cretaceous strata, especially in the Lower Greensand and at the base of the Gault.
The Cambridge Greensand, rich in phosphatic nodules, occurs at the base of the Chalk Marl.
At the base of the Red Crag in East Anglia, and occasionally at the base of the other Pliocene Crags, there is a " nodule bed," consisting of phosphatic nodules, with rolled teeth and bones, which were formerly worked as " coprolites " for the preparation of artificial manure.
Strutt has found that phosphatized nodules and bones are rich in radioactive constituents, and has brought this into relation with their geological age.
Over a large part of the central Pacific, far removed from any possible land-influences or deposits of ooze, the red-clay region is characterized by the occurrence of manganese, which gives the clay a chocolate colour, and manganese nodules are found in vast numbers, along with sharks' teeth and the ear-bones and other bones of whales.
As small concretionary nodules, it occurs disseminated through sandstone at Kommern in the Eifel.
For most of these the lightest spongy but sweet turfy peat must be used, this being packed lightly about the roots, and built up above the pot-rim, or in some cases freely mixed before use with chopped sphagnum moss and small pieces of broken pots or nodules of charcoal.
Nodules of 'pyrites have been found in prehistoric barrows and elsewhere under conditions suggesting their use as a primitive means of producing fire.
In coal it not infrequently forms bands and nodules known as "brasses," and may also be finely disseminated through the coal as "black pyrites"; but much of the so-called pyrites of coal is really marcasite.
Blende, is also found sporadically in sedimentary rocks; for example, in nodules of clay-ironstone in the Coal Measures, in the cement-doggers of the Lias, and in the casts of fossil shells.
Certain flat oval nodules from a decomposed lava (augite-andesite) in Uruguay present a cavity lined with quartz crystals and enclosing liquid (a weak saline solution), with a movable air-bubble, whence they are called "enhydros" or water-stones.
The lateral toes may be completely absent, but more often are represented by the hoofs alone, supported sometimes by a very rudimentary skeleton, consisting of mere irregular nodules of bone.
The nodules are not prepared in any way, but simply burned at a moderate red heat.
In the Cambrian limestones, as in their more recent analogues, layers and nodules of chert and phosphatized material are not wanting.
The work of numerous observers has shown that the free nitrogen of the atmosphere is brought into combination in the soil in the nodules filled with bacteria on the roots of Leguminosae, and since these nodules are the morphological expression of a symbiosis between the higher plant and the bacteria, there is evidently here a case similar to the last.
When these plants were examined they had small swellings or nodules on their roots, while those grown in sterile sand without soil-extract had no nodules.
Now these peculiar nodules are a normal characteristic of the roots of leguminous plants grown in ordinary soil.
They are clearly the result of infection (if the soil extract was boiled before addition to the sand no nodules were produced), and their presence enabled the plant to absorb the free nitrogen of the air.
The nitrogen of the air is absorbed by the nodules, being built up into the bacterial cell and later handed on to the host plant.
The green plant, however, always keeps the upper hand, restricting the development of the bacteria to the nodules and later absorbing them for its own use.
Ization of these bacteria to the leguminous plants has always been a very striking fact, for similar bacterial nodules are known only in two or three cases out _ side this particular /01 group. However, Pro fessor Bottomley an nounced at the meeting of the British Association for the Advancement of Science in 1907 that he had succeeded in breaking down this specialization and by a suitable treatment had caused bacteria from leguminous nodules to infect other plants such as cereals, tomato, rose, with a marked effect on their growth.
In this way secondary abscesses, secondary tubercle glanders and nodules, &c., result; in typhoid fever there is secondary invasion of the mesenteric glands, and clumps of bacilli are also found in internal organs, especially the spleen, though there may be little tissue change around them.
In limestones of various kinds it occurs as nodules and bands of chert and flint, being in this case of organic origin.
At Potton, phosphatized nodules may be obtained, and here a hard bed, the "Carstone," lies at the top of the formation.
The cells forming the limbs of the ectodermic folds secrete nodules of calcite, and these, fusing together, give rise to six (or twelve) vertical radial plates or septa.