Encrustive water

The presence of tubercles is usually obvious. Friable brown and orange nodular encrustations on mild steel and cast iron cooling water components are almost always tubercles (Figs. 3.12 through 3.14). The presence of a crust, shell, core, cavity, and corroded floor are definitive (Fig. 3.3). Careful analysis can provide considerable information concerning growth, chemical composition, and associated metal loss. 

Lac is derived from lac resin, the hardened secretion of the lac insect, the only known resin of animal origin. The lac insect, Kerria lacca, formerly known as Laccifer lacca, is a natural parasite of a variety of trees in large areas of southern Asia. Three different products are derived from lac resin lac dye, lac wax, and shellac. To obtain the lac resin, twigs encrusted with the secretion of the insects are cut down from the trees, then the incrustation is separated from the twigs, washed with water, and filtered. The wax and shellac, which are insoluble in water, remain as a solid residue of the filtration, while the soluble red dye (lac) is obtained as a powder when the water from the filtered solution is evaporated. The coloring matter in lac dye is an organic compound known as laccaic acid. 

In 1918 Miss Helene M. Boas, of the New York Botanical Garden, sent to the writer a sample of manna which had been collected by James A. Teit near Spence s Bridge, British Columbia, from Douglas fir trees (Pseudotsuga taxifolia Brit., syn. P. Douglasii Carr.). The dry, white, crystalline manna (42.5 g.), in which some small stems and needles of the tree (4 g.) were encrusted, was entirely soluble in water and it proved to consist principally of melezitose.17 The authors stated that if the manna can be obtained in large quantities, which appears to be the case, it will indeed furnish an excellent source for melezitose. However, there was found within a few months by the same workers an abundant... 

Conduction When a hot water sample is put into a freezer, it has been observed that the sample container sometimes melts the ice-encrusted surface, which then allows for much better heat conduction than the frost on which the colder container rests. As a result, heat is drawn from the warmer container more rapidly. 

Choose acidic formulations for products designed to dissolve soap scum, hard water spots, stains, rust, or encrustations that are mainly calcium or magnesium salts [10]. 

Cu and Zn enter sedimentary material in substantial proportions, both in the structure of minerals (carbonates, clays) and adsorbed on surfaces. Boyle (1981) showed that foraminiferal tests may contain Zn in excess of a few ppm. Partitioning of Cu and Zn between water and carbonates has been investigated by Rimstidt et al. (1998). The crystal chemistry of Cu and Zn in goethite has been investigated by EXAFS by Manceau et al. (2000). Typical Zn and Cu concentrations in FeMn nodules and encrustations are 500-1000 ppm and 800-6000 ppm, respectively (e.g., Albarede et al. 1997b). 

No arsine is evolved, but probably a trace of hydrogen results from the decomposition of water by the finely divided arsenic. The latter gradually encrusts the remaining realgar and prevents the reaction from proceeding to completion. It was the residue from this reaction that Berzelius 11 regarded as As S (see p. 237). 

Samples underwent sonication in hot, soapy water for 15 minutes, to ensure surfaces were clean and free of any surface contamination. The more elaborate preparation method of Carter (10, 13) was not utilized because visual and 7-30X microscopic examination of each coin revealed no remaining encrustation or patination. 

A thin (perhaps smaller than 6 p,m thick) hydrate shell grows around the water droplets, from small gas molecules dissolved in the oil phase. Initially this hydrate shell is extremely malleable, so much so the hydrate-encrusted droplet will extrude through screens, for example. 

Barnes, Ivan and Clarke, F. E. Chemical properties of ground water and their corrosion and encrustation effect on wells. U. S. Geol. Survey Prof. Paper 498-D, 58 p. (1969). 

Another surhcial deposit type includes the manganese-rich crusts and nodules that occur on basalt near mid-ocean ridges, and near the sediment-water interface. Whereas the ultimate source of manganese and iron (as well as the associated nickel, copper, and cobalt) is the hydrothermal alteration of MOR basalt, the fields of manganese-rich encrustations and nodules that cover large areas of sediment-starved ocean floor are the result of surficial authigenic upward remobilization of metals and the fixing of those metals at the sediment-water interface. 

Some calcium and other minerals are found naturally in any water that has percolated through the ground. So if the swimming pool is allowed to become too alkaline, it will grow cloudy, at best, with suspended particles of insoluble salts or encrusted with growths of scale at worst. This appearance of a solid in a liquid solution is called precipitation, just as rain is called precipitation, because of the propensity of the solids to come out of the solution just as rain comes out of the sky. 

At great ocean depths or in areas with poor visibility other devices may be employed. Sonar may be used to determine the location of large or encrusted objects by calculating the time it takes echoes to bounce off them. Underwater cameras may be towed by the boat to take pictures of a site in water with good visibility. 

The ability to reduce bacterial surface numbers or promote one type of bacterium over another and thereby encourage certain physical surface conditions, may be a beneficial adaptation employed by some bryozoans against fouling. Extracts from four species of bryozoans, found in Tasmanian coastal waters, have been demonstrated to exhibit selective antibacterial activity (49]. The four species showed gradations in fouling by encrusting organisms and differential bacterial numbers. 

The red algae are the most prominent and widely distributed carbonate-depositing algae. They occur in the northern seas as well as in the tropical waters and become encrusted in the intertidal zone as well as in water depths exceeding 50 m. 

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