The hardness came back into his eyes and he looked away.
It is an ironblack, opaque mineral, with metallic lustre; hardness about 6, sp. gr.
But this " critical value " of the force is found to depend in an unexpected manner upon the hardness of the steel; the critical value diminishes as the hardness becomes greater up to a certain point, corresponding to a yellow temper, after which it increases and with the hardest steel becomes very high.
A greater hardness is due to the presence of earthy impurities.
The iron-bark of the eastern coast uplands is well known (Eucalyptus sideroxylon), and is so called from the hardness of the wood, the bark not being remarkable except for its rugged and blackened aspect.
The I heart-wood ceases to be of any use to the tree except as a support, but owing to its dryness and hardness it alone is of much use for industrial purposes.
The experiments were not sufficiently numerous to indicate whether, as is possible, there is a critical degree of hardness for which the height of the elongation curve is a maximum.
The hardness is 2, and the specific gravity 2 I.
For building and miscellaneous purposes, in addition to the rare woods above named, there are cedars (used in great quantities for cigar boxes); the pine, found only in the W., where it gives its name to the Isle of Pines and the province of Pinar del Rio; various palms; oaks of varying hardness and colour, &c. The number of alimentary plants is extremely great.
The hardness is 2 -3; smooth cleavage surfaces can be just scratched with the finger-nail.
You get used to knowing the different types of hardness and thickness.
Its hardness is rather above 5, and its specific gravity varies from 3.5 to 4.
There are certain instances in his life which, taken by themselves, show a hardness in treating individuals who would not obey; but as a rule, he tempered his authority to the capacity of those with whom he had to deal.
Then the boy returned to one of the upper rooms, and in spite of the hardness of the glass bench was soon deep in slumberland.
His warm hands covered hers and she could feel the hardness of his chest muscles on her back as he guided her arms in a smooth swing.
Hardness 31-4; sp. gr.
When the waters evaporate in the summer they leave a clay bed of remarkable hardness, which is sometimes encrusted with saline matter of a snowy whiteness and dazzles the eyes of the traveller.
For example, the physicist determines the density, elasticity, hardness, electrical and thermal conductivity, thermal expansion, &c.; the chemist, on the other hand, investigates changes in composition, such as may be effected by an electric current, by heat, or when two or more substances are mixed.
They were certainly originally stone-quarries, and the hardness of the rock has made the construction practicable of wide, lofty of corridors and spacious halls, very unlike the narrow galleries and contracted chambers in the Roman cemeteries.
A high silica-content tends towards both hardness and chemical stability, and this can be further increased by the addition of small proportions of boric acid; in larger quantities, however, the latter constituent produces the opposite effect.
The difference between softness and hardness in ordinary steel is due to the permanence of a solid solution of carbon in iron if the steel has been chilled or very rapidly cooled, while if the steel is slowly cooled this solid solution breaks up into a minute complex of two substances which is called pearlite.
In the alluvial deposits the associated minerals are chiefly those of great density and hardness, such as platinum, osmiridium and other metals of the platinum group, tinstone, chromic, magnetic and brown iron ores, diamond, ruby and sapphire, zircon, topaz, garnet, &c. which represent the more durable original constituents of the rocks whose distintegration has furnished the detritus.
When not tarnished, the mineral has a silver-white colour with a tinge of red, and the lustre is metallic. Hardness 2-21; specific gravity 9-70-9.83.
The ridges and intervening valleys, long parts of which have an approximately parallel trend from south-west to north-east, were formed by the erosion of folded sediments of varying hardness, the weak belts of rock being etched out to form valleys and the hard belts remaining as mountain ridges.
They have the property of entering into chemical combination with the lime, forming a hard setting compound, and increasing the hardness of the resulting concrete.
Hence the changes of volume undergone by a given sample of wrought iron under increasing magnetization must depend largely upon the state of the metal as regards hardness; there may be always contraction, or always expansion, or first one and then the other.
According to lapidaries the hardness of sapphire slightly exceeds that of ruby, and it is also rather denser.
When quite pure it is somewhat harder than tin, and its hardness is considerably increased by rolling.
The metal produces an enormous number of useful alloys, some of which, containing only i or 2% of other metals, combine the lightness of aluminium itself with far greater hardness and strength.
The heat of his bare chest beneath her hands and the hardness of his arousal against her belly made need roar to life within her.
Succinite has a hardness between 2 and 3,.
The great hardness of teak is due to the silica deposited in the heart-wood, and the special coloring matters of various woods, such as satinwood, ebony, &c., are confined to the heart-wood.
The hardness ranges from about I to 2, and the sp.gr.
Semitransparency, brilliancy and hardness are, however, also essentials.
It is certain that the structure existing in the alloy is closely connected with the mechanical properties, such as hardness, toughness, rigidity, and so on, that make particular alloys valuable in the arts, and many efforts have been made to trace this connexion.
The maximum hardness is from 2.5 to 3 in anthracite and hard bituminous coals, but considerably less in lignites, which are nearly as soft as rotten wood.
The characters of softness or hardness, dryness or moisture, &c., are taken account of in these classifications.
An important character, and one by which the mineral may always be recognized, is the perfect cubical cleavage, on which the lustre is brilliant and metallic. The colour of the mineral and of its streak is lead-grey; it is opaque; the hardness is 2 2 and the specific gravity 7.5.
Notwithstanding its hardness it has been sometimes engraved as a gem.
Then her attention was called to the hardness of the one ball and the softness of the other, and she learned SOFT and HARD.
Thick, and formed of a core of rough rubble cemented together with mortar (containing much coarse gravel) of extraordinary hardness and tenacity, and a facing for the most part of stone - Kentish rag, freestone or ironstone - but occasionally of flints; about 2 ft.
Hauran southward forms the main watershed of the peninsula is covered in places by deep beds of lava, which from their hardness have preserved the underlying sandstones from degradation, and now stand up consider ably above the general level.
The hardness is 51-6, and the specific gravity 5.9-6.2.
There is still controversy as to what degree of hardness, or (which is nearly the same thing) what percentage of carbon, can be permitted with safety in steel for structures.
Although it contains a higher percentage of metal (5 2.9%) than any other natural compound, it is not at present employed as an ore, not only because it is so hard as to be crushed with difficulty, but also because its very hardness makes it valuable as an abrasive.
The territories of the Gran Chaco, however, are covered with a characteristic tropical vegetation, in which the palm predominates, but intermingled south of the Bermejo with heavy growths of algarrobo, quebracho-colorado, urunday (Astronium fraxinifolium), lapacho (Tecoma curialis) and palosanto (Guayacum officinalis), all esteemed for hardness and fineness of grain.
Boron dissolves in molten aluminium, and on cooling, transparent, almost colourless crystals are obtained, possessing a lustre, hardness and refractivity near that of the diamond.
Made of exceedingly refractory clay, it under went stoving for more than three weeks, and was consequent!) remarkable for its hardness and metallic timbre.
During the three years he held this position he carried out researches on the contact of elastic solids, hardness, evaporation and the electric discharge in gases, the last earning him the special commendation of Helmholtz.
Carbon is the important element in controlling hardness, and the amount present is in general higher in the United States than in Great Britain.
The shape of the hills and ridges is necessarily influenced by the inclination of the strata, by the relative hardness of different rock-beds, and by the presence of folds and fissures and other lines of weakness.
Some experiments were next undertaken with the view of ascertaining how far magnetic changes of length in iron were dependent upon the hardness of the metal, and the unexpected result was arrived at that softening produces the same effect as tensile stress; it depresses the elongation curve, diminishing the maximum extension, and reducing the " critical value " of the magnetizing force.
Marcianus, and the type is different from that of the Roman catacombs, the galleries being far larger (partly owing to the hardness of the limestone in which they are excavated), and having circular chambers at the points * of junction.
Such an alloy can be cast like ordinary bronze, but excels the latter in hardness, elasticity, toughness and tensile strength.
Considerations of growth determine to a great extent the hardness or softness, and strength or weakness, of the fibre, and thus, indirectly, whether the cotton is suitable for warp or weft.
They are full of both grace and individuality; the features show excellent draughtsmanship; and the flesh-painting is firm and sound in method, though frequently tending a little to hardness and opacity.
By the "hardness" of a metal we mean the resistance which it offers to the file or engraver's tool Taking it in this sense, it does not necessarily measure, e.g.
Most natural waters contain it dissolved in carbonic acid; this confers "temporary hardness" on the water.