Conferences Held in Connection with the Special Loan Collection of Scientific Apparatus, 1876: Chemistry, Biology, Physical Geography, Geology, Mineralogy, and MeteorologyLords of the Committee of Council on Education, 1876 - Scientific apparatus and instruments - 441 pages |
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Conferences Held in Connection with the Special Loan Collection of ... South Kensington Museum No preview available - 2016 |
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action ammonia amount anemometers aniline aniline black animal apparatus atmosphere barley barometer Bessemer process canals carbonic acid cent chemical coal colour combined nitrogen compounds connected containing copper crops cryohydrate crystals diffusion doubt electrical employed exhibited experiments fact feet flora freezing freezing mixture gases gauge Geological Survey give glass Graham horizontal hydrogen inches instrument interesting investigation leguminous light liquid magnetic manganese manure maps means measure melting mercury metal method microtome mineral Miocene mixture molten mass muscle nitrate nitric acid nitrogen observations obtained ordinary oxide oxide of iron oxygen ozone paper passing plants plate platinum present PRESIDENT pressure produced Professor quantity question rain remarkable rocks salt scientific Siemens-Martin process Silurian soil solution specimens steel substance surface temperature tion tube vanadium velocity vessel weight wheat William Snow Harris wind wire
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Page 132 - Although chemically inert in the ordinary sense, colloids possess a compensating activity of their own, arising out of their physical properties. While the rigidity of the crystalline structure shuts out external impressions, the softness of the gelatinous colloid partakes of fluidity, and enables the colloid to become a medium for liquid diffusion, like water itself.
Page 133 - Placed in pure water, such colloids (as animal membrane) are hydrated to a higher degree than they are in neutral saline solutions. Hence the equilibrium of hydration is different on the two sides of the membrane of an osmometer. The outer surface of the membrane being in contact with pure water, tends to hydrate itself in a higher degree than the inner surface does, the latter surface being supposed to be in contact with a saline solution.
Page 127 - It seems that molecules only can pass ; and they may be supposed to pass wholly unimpeded by friction, for the smallest pores that can be imagined to exist in the graphite must be tunnels in magnitude to the ultimate atoms of a gaseous body. The sole motive agency appears to be that intestine movement of molecules which is now generally recognized as an essential property of the gaseous condition of matter.
Page 129 - ... to observe that the phenomena of effusion and diffusion are distinct and essentially different in their nature. The effusion movement affects masses of gas, the diffusion movement affects molecules ; and a gas is usually carried by the former kind of impulse with a velocity many thousand times greater than by the latter.
Page 24 - How much, however, mightthus be available beyond that determined in the collected and measured aqueous deposits, the existiii!.' evidence does not afford the means of estimating with any certainty. The next point to consider is — What is the amount of nitrogen annually obtained over a given area, in different crops, when they are grown without any supply of it in manure ? The field experiments at Rothamsted supply important data relating to this subject. Thus, over a period of 32 years (up to 1875...
Page 131 - Founding still upon the chemical atoms, we may suppose that they can group together in such numbers as to form new and larger molecules of equal weight for different substances, or, if not of equal weight, of weights which appear to have a simple relation to each other.
Page 129 - It appears then that the times of passage through the graphite plate have no relation to the capillary transpiration-times of the same gases first quoted above. The new times in question, however, show a close relation to the square roots of the densities of the respective gases, as is seen in the last Table ; and so far they agree with theoretical times of diffusion usually ascribed to the same gases. The experiments were varied by causing the gases to pass into a Torricellian vacuum, and consequently...
Page 38 - One view which has been advocated is, that broad-leaved plants have the power of taking up combined nitrogen from the atmosphere, in a manner, or in a degree, not possessed by the narrow-leaved gramineous plants. The only experiments that we are aware of, made to determine whether plants can take up nitrogen by their leaves from ammonia supplied to them in the ambient atmosphere, are those of Adolph Mayer in Germany, and of Schlosing in France.
Page 22 - ... maintained that its source must be water ; and that the source of the oxygen was either that contained in carbonic acid or that in water. With regard to the nitrogen of vegetation, both from the known characters of free nitrogen, and as he considered a legitimate deduction from direct experiments...
Page 128 - Robison from Torricelli's well-known theorem of the velocity of efflux of fluids. A gas rushes into a vacuum with the velocity which a heavy body would acquire by falling from the height of an atmosphere composed of the gas in question, and supposed to be of uniform density throughout. The height of the uniform atmosphere will be...