Density

“ It is therefore reasonable to assume that the density increases as we descend; nor is there any sufficient ground for thinking that the earth is much heavier in one part than at any other part equally remote from the centre. It is therefore usual in such calculations to assume that the earth is formed of concentric spherical shells, each one of which is of uniform density; while the density decreases from each shell to the one exterior thereto. ”

“ The surface-density when positive is of the same order of magnitude as the thickness of the non-homogeneous film, but is not necessarily small compared with other surface-densities because the volume-densities of the same substance in the adjacent masses are small. Now the potential of a substance which forms a very small part of a homogeneous mass certainly increases, and probably very rapidly, as the proportion of that component is increased. ”

“ They are illustrations of the general fact that when the density varies rapidly with the temperature, determinations of density for the same temperature and pressure by different observers, or different determinations by the same observer, exhibit discordances which are entirely of a different order of magnitude from those which occur with substances of normal or constant densities, or which occur with the same substance at temperatures at which the density approaches a constant value. ”

“ In every case that density has been found to be much less than the sun's, and indeed the average of a number of mean densities which have been determined only amounts to one-eighth of that of the sun. ”

“ The density of chalk is twice as great as the density of water, because a cubic centimeter of chalk weighs twice as much as an equal volume of water, and similarly in other cases the density is found by dividing the mass or weight of the body by the mass or weight of an equal volume of water. ”

“ When we determine the mean density of the earth, it is not because any part of the earth is of that exact density; there may be no part exactly corresponding to the mean density, and as the crust of the earth has only about half the mean density, the internal matter of the globe must of course be above the mean. Even the density of a homogeneous substance like carbon or gold must be regarded as a mean between the real density of its atoms, and the zero density of the intervening vacuous space. ”

“ There are different sorts of Densities and Rarities, Softness and Hardness, Levities and Gravities: as for example, The density of Earth is not like the density of Stone; nor the density of Stone, like the density of Metal: nor are all the Parts of the Earth dense alike ”

“ If a fluid be composed of particles mutually flying each other, and the density be as the compression, the centrifugal forces of the particles will be reciprocally proportional to the distances of their centres. And vice versa, particles flying each other with forces that are reciprocally proportional to the distances of their centres, compose an elastic fluid, whose density is as the compression. ”

“ We find, therefore, the idea thrust upon us that there may be a limit to density, perhaps not an absolute limit, but a practical one; in which case, the greatest density of the earth may not greatly exceed 5·66 times that of water. ”

“ Multiplying the number of units of density of a portion of matter, by the number of units of space occupied by it, we arrive at the quantity of matter, or, as it is usually called, the unit of mass, as indicated by the inertia and gravity it possesses. To proceed in the most simple manner, the unit of mass ought to be that of a cubic unit of matter of the standard density ”

“ The quantity within brackets rapidly approaches unity as increases, so that at a distance from the boundary equal to times the breadth of the strip , the actual density is greater than the normal density by about of the normal density. ”

“ In the case of solids we may determine the volume in some cases by direct measurement—this gives at the best a very rough and ready value; a better method is to immerse the body in a fluid (in which it must sink and be insoluble) contained in a graduated glass, and to deduce its volume from the height to which the liquid rises. The weight may be directly determined by the balance. The ratio “weight to volume” is the absolute density. ”

“ If all the solid particles of all bodies are of the same density, nor can be rarified without pores a void space or vacuum must be granted. By bodies of the same density, I mean those, whose vires inertia are in the proportion of their bulks. ”

“ Instead then of saying that the density of the ether is great, the clearest mode of expression is to say that the density of matter is small. Just as we can say that the density of the visible cosmos is small, although in individual lumps its density is comparable to that of iron or rock. ”

“ It follows absolutely that the density of the materials of the Earth's interior must be considerably in excess of 5.5. If the interior is composed chiefly of substances which are plentiful in the Earth's surface strata, our choice of materials which principally compose the interior is reduced to a few elements, notably the denser ones. ”

“ The absolute density is, therefore, unity for an atom, and varies from 0 to 1 for all bodies.”
If two bodies have the same apparent volume, their densities are proportional to their masses.
I have been looking through a capital French work on Chemistry, published in 1870, by M. Alfred Riche, lecturer at the Polytechnic School at Paris. He uses the old notation and table of equivalents; but strongly advises a change to the new, which he explains very nicely, and pretty much as our lecturer has done. ”

“ But whether the assumption of uniform density be physically correct is a very different question, and Poisson rendered good service to science in showing how to carry on the investigation on the hypothesis that the density very near the surface is different from that in the interior of the fluid. ”

“ Assuming the density of the earth to be 512 times that of ice, it follows that, if a globe of ice—say ten miles in diameter—be isolated in space, a small dense body, as a bullet, near its surface, should fall toward it—by the action of its gravity alone—through 160 inches during the first minute of its descent. ”

“ As we proceed in the consideration of our general subject, we shall find, under the appropriate heads, that density is not without material influence on reflection and refraction, on transparency and the transmission of light, the presence or absence of moisture, and the amount of heat at the earth's surface,- -and we might add, on health, and the increase or diminution of the vital energies. ”

“ We may here notice the different action of traces in the homogeneous masses of those substances which increase the tension and of those which diminish it. When the volume-densities of a component are very small, its surface-density may have a considerable positive value, but can only have a very minute negative one. [23] For the value when negative cannot exceed (numerically) the product of the greater volume-density by the thickness of the non-homogeneous film. ”

“ For impurities which increase the density would make the divergence between the different series greatest when the densities are the least, whereas the divergences seem to vanish as the density approaches the limiting value. ”

“ The shrinkage of a constant mass of matter involves an increase of its density, and we have therefore to trace the changes which supervene as the star shrinks, and as the liquid of which it is composed increases in density. ”

“ Emily. It is then, I suppose, owing to the different degrees of cohesive attraction in different substances, that they are hard or soft, and that liquids are thick or thin.
[Pg 16]
Mrs. B. Yes; but you would express your meaning better by the term density, which denotes the degree of closeness and compactness of the particles of a body. In philosophical language, density is said to be that property of bodies by which they contain a certain quantity of matter, under a certain bulk or magnitude. Rarity is the contrary of density ”