Salt polishing

Nowak, L., Regel-Rosocka, M., Marszalkowska, B., and Wisniewski, M. 2010. Removal of Zn(ll) from chloride acidic solutions with hydrophobic qnatemary salts. Polish Journal of Chemical Technology 12 24-28. 

Since most sample holders have some type of alkali metal-halide window, a brief discussion of salt polishing is in order. It is not difficult for the spectroscopist to prepare and polish salt plates. If the NaCl is bought as a crystalline block, it can be cleaved into suitable windows with a single edged razor which is hit with a small hammer or screw driver shaft. When a cleavage is started, it is followed until complete. Blocks may be split into halves or thirds safely, but if much smaller sections are cleaved from the block, the smaller pieces may break. The halves of thirds can then be split. The cleavage planes are usually (but not always) parallel to the planes of the uncleaved block. NaCl and KBr will cleave but CsBr does not cleave and plates are bought preshaped. 

A whole science, called metallography, is devoted to this. The oldest method is to cut the alloy in half, polish the cut faces, etch them in acid to colour the phases differently, and look at them in the light microscope. But you don t even need a microscope to see some grains. Look at any galvanised steel fire-escape or cast brass door knob and you will see the grains, etched by acid rain or the salts from people s hands. 

Metall-oxyd, n. metallic oxide, -oxydhydrat, n. metal (lie) hydroxide, -papier, n. metal (lie) paper, -poliermittel, n. metal polish, -probe, /, test for metal, assay, -putzmittel, n. metal polish, -rohr, n., -rbhre, /. metal tube oi-pipe, -rohrehett, n. (small) metal tube or pipe, -riickstand, m. metallic residue, -sa-fran, m. crocus of antimony, -salz, n. metallic salt. 

Salt that sticks to the sides of the Erlenmeyer flask may be loosened with a piece of 10-mm. glass tubing that has not been fire-polished. 

A chemical polishing mixture was put into a closed glass bottle which burst 30 min later, and formation of silver fulminate was suggested. However, in absence of the silver salt such mixtures evolve gas and should not be stored in any event, especially after use for metal polishing, when the dissolved metal(s) tend to further destabilise the mixture. 

The pigment, P(s), can, in principle, be any seawater-soluble particulate solid that is being considered for a potential use in a self-polishing antifouling paint. Salts, sugars, and proteins (enzymes, peptides, or hormones) are obvious examples. It should be noted that the pigment can also represent a seawater-... 

Figure 8.7 shows such a flow plot for the radical cation of the viologen species, l,l -bis(p-cyanophenyl)-4,4 -bipyridilium ( CPQ ), as the bis(tetrafluoroborate) salt in propylene carbonate solution, with the radical having been formed at a polished platinum electrode. The plot is seen to be linear, implying that, once formed, the CPQ radical cation is chemically stable. 

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