Natural earths

Ochers and siennas Natural earths, mixtures of silica and iron oxides... 

Firmly in the iatrochemical tradition, Homberg believed that the analysis by fire revealed the familiar five principles, salt, sulphur, mercury, WATER, and EARTH. SuLPHUR was the active and earth the passive principle, the others having an intermediate nature. Earth never acts, but serves only as a receptacle or matrix for the other principles.These, of course, were the philosophical principles, and he spent some time describ-... 

It will be noted that the term gypsum is used by Theophrastus, as indeed by later ancient writers, to indicate the dehydrated sulphate of lime (plaster of Paris), rather than the mineral (gypsum) from which it is obtained, though he elsewhere alludes somewhat vaguely to certain natural earths under that name. 

Behaviour with Lead Peroxide.—A little of the substance is boiled for a few moments with nitric add and lead peroxide after standing, the liquid appears red owing to the presence of manganese with the natural earth the coloration is, however, slight, whilst with the burnt earth it is much more intense. It is well to make this test in comparison with typical products. 

Natural umbers contain somewhat variable amounts of hygroscopic water (up to 20% or more), and the loss on ignition usually varies from 7 to 11%. The dried earth contains much less hygroscopic moisture (about 6%),but the whob of the combined water, so that the loss on Calcination is the same as with the natural earths. The burnt earth contains little hygroscopic water (usually less than 5%) and give a loss of 3-4% on calcination. In general it may be said that when an umber loses less than 5% on calcination, it is burnt —this independently of the hygroscopic water, which may be considerable even in burnt umber if this has been stored in a moist place. 

The constituent character of sulphur was inflammability. There existed at least three kinds of sulphurs, however, manifestly differing in consistence, texture, or both oils, inflammable spirits, and consistent sulphurs such as common sulphur. The imprecision in terminology was just as evident here as in the case of spirits. What chemists normally called sulphur, or common sulphur, was a mineral body. The two qualities chemists attributed to phlegm or water were its appearing to them insipid, and its being of a volatile and fugitive nature. Earth seemed the most simple, elementary, and unchangeable principle it did not dissolve in water, did not affect the taste, and did not fly away from the body in combustion. ... 

The above results make it very clear that forecasts of the future oxidation capacity of the atmosphere depend critically on the assumed emissions. The IPCC did not assign probabilities to its emission scenarios but it is apparent that some of these scenarios are highly improbable for oxidant precursor emissions. Integrated assessment models, which couple global economic and technological development models with natural Earth system models provide an alternative approach to the IPCC scenario approach with the added advantage that objective estimates of individual model uncertainties can be combined with Monte Carlo approaches to provide more objective ways of defining means and errors in... 

Table 2 gives a comparison of the six heavy-metal contents of a variety of natural earth materials that annually impact atmospheric, terrestrial, and aquatic environments. The primary data of metals are also normalized with respect to titanium (Ti). Titanium is a very conservative element that is associated with crustal rock sources. Normalization with respect to Ti compensates... 

Table 2 Average concentration of six heavy metals in natural earth materials. 

Ceramic materials have been made since well before the dawn of recorded history. They are generally fashioned from clay or other natural earths at room temperature and then permanently hardened by heat. Silicate ceramics include objects made from clays, such as pottery, bricks, and table china. The three major ingredients of common pottery are clay (from weathering of feldspar as described previously), sand (silica), and feldspar (aluminosilicates). Clays mixed with water form a moldable paste because they consist of many tiny silicate sheets that can easily slide past one another. When the clay-water mixture is heated, the water is driven off, and new Si—O—Si bonds are formed so that the mass of platelets becomes permanently rigid. 

Other ancient examples of the use of natural earths and minerals include the application of bitumen as a hot melt adhesive to stick rocks together, known in... 

In industrial practice, although some copper catalysts have been used, it is customary to use dry or wet reduced nickel catalysts supported on a natural earth such as kieselguhr and suspended in an hydrogenated fat, usually hardened palm or soybean oil. The nickel content of the commercial catalyst is between 17 and 25% and a similar amount of earth is incorporated. 

Stray electric currents are those that follow paths other than the intended circuit, or they may be any extraneous currents in the earth. If currents of this kind enter a metal structure, they cause corrosion at areas where the currents leave to enter the soil or water. Usually, natural earth currents are not important from a corrosion standpoint, either because their magnitude is small or because their duration is short. Under some conditions, pipelines can incur considerable corrosion damage as a result of telluric currents—that is, currents induced in the steel pipeline by changes in the geomagnetic field of the earth [1]. 

Natural gas— A combustible gas composed largely of methane and other hydrocarbons obtained from natural earth fissures. 

Lime biue Mixture of ultramarine and terra alba. Another type of lime blue is made from methylene blue by adsorption on natural earth. 

Lime red Lake produced by adsorbing magenta on a natural earth. 

Red ocher (1572) n. A mixture of hematites any of a number of natural earths used as red pigments. 

Vandyke brown van- dlk braun [fr. its use by the painter Vandyke] (ca. 1850) n. (1) A very dark, deep-brown natural earth pigment consisting essentially or organic matter obtained from peat or lignite found chiefly in parts of Germany its principal uses are in artists colors, stains and graining. (2) A synthetic pigment of similar color. 

Reinforced concrete bases and spiral steel bases of PV modules should be fully used as natural earth-termination system. The impulse resistance value of earth-termination systems should be less than 10 In areas with high value of soil resistivity, it is allowable to appropriately increase the value, but this value should not be greater than 30 When connecting the artificial... 

Cement Colorants n Term used to describe colors with sufficient tinctorial strength and alkali resistance to be suitable for coloring Portland cement or concrete. The natural earth colors, synthetic iron oxide colors, chromium oxide, ultramarine, and some of the organic pigments are used for this purpose. 

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