Color, names based

Nomenclature before Werner (to 1897)- The Lavoisierian system of nomenclature, even with the Berzelius modifications, provided no suitable names for that class of compounds which later was designated coordination compounds. Names based on the patterns for double salts and addition compounds were not satisfactory because the properties of these materials were not those consistent with the patterns provided. Consequently, names based on properties, especially color (Table I), or the names of prominent investigators became popular (2) because they, at least, did not commit the user to any theory of their structure. The developments in organic chemistry after 1860 did not contribute to the understanding of these strange compounds, so there was no carry-over to them of the nomenclature developments in organic chemistry. 

Despite Werner s antipathy for names based on color, such names were generally used well into the present century. For example, the name luteo, originally proposed for [Co(NH3)6]", was generalized to include [Co(en)3] [Co(bipy)3] [Co(trien)2] and other cobalt compounds in which six amine nitrogen atoms are coordinated to cobalt (or even other metal ions) in the luteo series. As long as cobalt and chromium were the only metal ions included, the reference to color had real meaning. However, to consider colorless [Ru(NH3)6]" (16) as a member of the luteo series was, to say the least, somewhat ambiguous. 

Philosophy of direct application of foreign substitutes of tooth color is based on two pillars, namely RC and GIC, and their various qualitative and quantitative combinations, variations, hybridizations. RC s provide strong arguments for their potentially superior abilities of accurate imitation of the tooth hard tooth stmctures. On the other hand, pejorative resonance still accumulates in the complicated and ineffective over time, especially from the practical point of view, the adhesive technology, and... 

R , they could be made soluble in their undoped form, and that they could be doped [264, 566]. P(DiAc)s are typically named on the basis of die substituents R, R used. Some of the most common P(DiAc)s, and several others, are listed in Fig. 13-7 below. Many P(DiAc)s display thermochromism and solvatochromism (color changes based on temperature and solvent composition changes), e.g. yellow to red or blue. [567]. Indeed a thermochromic shift in Raman spectra has been observed. Photocurrent behavior in single crystals of PTS and MADF, two P(DiAc)s witli different substituent groups (Fig. 13-7 is very different [568], demonstrating the strong influence of the substituent groups in this class of CPs. 

Name pH Range Color Change Acid to Base Indicator Solution... 

Portland cement is classified as a hydrauHc cement, ie, it sets or cures in the presence of water. The term Portland comes from its inventor, Joseph Aspdin, who in 1824 obtained a patent for the combination of materials referred to today as Portland cement. He named it after a grayish colored, natural limestone quarried on the Isle of Portland, which his cured mixture resembled. Other types of hydrauHc cements based on calcium materials were known for many centuries before this, going back to Roman times. Portland cement is not an exact composition but rather a range of compositions, which obtain the desired final properties. The compounds that make up Portland cements are calcium siHcates, calcium aluminates, and calcium aluminoferrites (see ). 

The demand for cement was stimulated by the growth of canal systems ia United States duting the nineteenth century. Process improvements were made ia the calciaation of certain limestones for the manufacture of natural cements, which were gradually displaced by Pordand cement. This latter was named ia a 1824 patent because of its color and resemblance to a natural limestone quarried on the Isle of Pordand ia England. Research conducted siace that time has provided a clear picture of the composition, properties, and fields of stabiUty of the principal systems found ia Pordand cement. These results led to the widely used Bogue calculation of composition based on oxide analysis (1). Details beyond the scope of this article may be found ia the Hterature (2). 

Pipework should be easily identifiable in accordance with BS 1719. Where the normal pressure in the pipe exceeds 75mbar, consideration should be given to labeling the pipe with the normal operating pressure. In buildings in which there are no other piped flammable gas supplies it is sufficient to paint the pipe yellow ochre or to band it with appropriately colored adhesive tape. In large complex installations, it is desirable to identify pipe contents more precisely, and in those instances, the base color should be supplemented with a secondary code band of yellow and/or its name or chemical symbol. 

The common names for the allotropes of element v are based upon their colors. 

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