Chapter 4 – Tests for the Elements, their Ions and Compounds
01 Jan 1972-pp 94-524
About: The article was published on 1972-01-01. It has received 6 citations till now.
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TL;DR: Since the mid-19th century, various pest eradication techniques have been employed on the anthropology collections at the National Museum of Natural History, Smithsonian Institution as mentioned in this paper, and these techniques are reviewed, and pesticide and fumigant use by early collectors and later collections management staff is documented.
Abstract: Since the mid-19th century, various pest eradication techniques have been employed on the anthropology collections at the National Museum of Natural History, Smithsonian Institution. These techniques are reviewed, and pesticide and fumigant use by early collectors and later collections management staff is documented. Also chronicled are the ways in which the choice of chemicals has changed over the years and the decisions that led to those changes. The effects of pest eradication techniques on the collections are discussed, and the author's findings are offered as the basis for further research.
63 citations
TL;DR: In this paper, the main features, molecular structures and physical and chemical properties of these carbon types, so far as they are relevant to pigment studies, are reviewed in outline and some better-known pigments based on carbon are summarized, with an indication of which form or forms of carbon each contains.
Abstract: A primary classification of carbons is into crystalline and non-crystalline forms. The only crystalline carbon encountered as a pigment is graphite; a secondary classification for non-crystalline forms is into flame carbons (formed in the gas phase), cokes (formed in a liquid or plastic phase), chars (formed entirely in the solid phase) and natural forms such as coal. The main features, molecular structures and physical and chemical properties of these carbon types, so far as they are relevant to pigment studies, are reviewed in outline. Some better-known pigments based on carbon are summarized, with an indication of which form or forms of carbon each contains. X-ray diffraction patterns for graphites, and for examples of the non-crystalline types, are described and discussed. Particle morphology of various carbons and pigments, as elucidated from scanning electron micrographs, is described in some detail, and notes are added on the use of optical microscopy in studying these materials.
48 citations
TL;DR: In this paper, the Freer collection of Japanese paintings of the twelfth to the sixteenth centuries has been determined, and basic lead carbonate (lead white) was found in 12 out of 13 Chinese paintings and in all three Korean paintings.
Abstract: Japanese paintings of the twelfth to the sixteenth centuries in the collection of the Freer Gallery of Art has been determined. In 12 out of 13 Chinese paintings, and in all three Korean paintings, basic lead carbonate (lead white) was found. Of the 29 Japanese paintings, six had basic lead carbonate, 20 had basic lead chloride (which occurred as two different compounds), and two carried both of these species. One Chinese painting had lead sulphate and one Japanese painting lead phosphate. Historical evidence suggests that two forms of 'lead white' were known and distinguished during the eighth century in Japan; the possible connection between this and the present findings on Japanese paintings is discussed.
16 citations
TL;DR: The outlook and likely impact of these tests on the expansion of scientific investigation and legacy and technical details of selected spot tests used in solving crime are described.
Abstract: Chemical spot tests are one of the oldest and simplest presumptive methods of analytical chemistry. They are an integral part of the schematic analysis of different types of substances in various pure and applied scientific disciplines including forensic science. The role of spot tests has remained eternal utility in different branches of forensic science to analyze various types of physical or trace evidences. Forensic experts need to have an absolute understanding of the foundation and technicality behind complex reactions of customary spot tests. Forensic science literature dwells in the diversity of spot tests but an informative and comprehensive compendium of such prose remains occasional and limited in general. Keeping in view the ample history and legacy of spot test, the current review was constructed from a core of historical literature to recapitulate trending applications, chemistry, and limitations of notable "Griess test", "Luminol test", "Kastle-Meyer test", "Phenolphthalein test", "Ninhydrin test", and "Spy dust" in forensic science. The aim of this review article was to describe the outlook and likely impact of these tests on the expansion of scientific investigation. The anticipated output of this review is supposed to impart compatible knowledge in the attentive readers interested in understanding legacy and technical details of selected spot tests used in solving crime.
7 citations
TL;DR: In this article, the corrosion products on a silver dragon suspected to have been treated with cyanide revealed both silver cyanide and chalconatronite, which can be formed on silver objects cleaned or replated using a cyanide solution.
Abstract: Analysis of the corrosion products on a silver dragon suspected to have been treated with cyanide revealed both silver cyanide and chalconatronite. It appears that both of these corrosion products can be formed on silver objects cleaned or replated using a cyanide solution. These corrosion products darken with exposure to light; therefore, they may be mistaken for silver sulfide. In order to determine how to remove the highly poisonous cyanide corrosion product, numerous tests were run. Using a carefully timed procedure the silver cyanide was removed with an aqueous solution of 20% sodium thiosulfate. The chalconatronite was removed mechanically.
5 citations
References
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TL;DR: In this paper, the liquid-liquid extraction of chromium as [(C6H5)3Se]2Cr2O7 allows the determination of 25 μg Cr in cast-iron and steels, containing manganese, vanadium and molybdenum.
Abstract: ZusammenfassungEs werden die Extraktions- und Fällungsreaktionen komplexer Übergangsmetall-Anionen untersucht. Durch geringe Löslichkeiten zeichnen sich u. a. das Triphenylselenonium-Dichromat, Perchlorat und -Molybdat aus (Wolframat leicht löslich). Die Verbindung [(C6H5)3Se]2 Cr2O7 ist quantitativ extrahierbar, [(C6H5)3Se]ClO4 eignet sich zum Nachweis von ClO4−-Mengen ab 5 μg neben großen Mengen ClO3−. Die extraktiv-photometrische Bestimmung von Chrom als [(C6H5)3Se]2Cr2O7 ermöglicht die Ermittlung von 25 μg Cr neben Mangan und Vanadium in Stählen verschiedenster Zusammensetzung. In Triphenylselenoniumverbindungen kann das Kation als [(C6H5)3Se][B(C6H5)4] gravimetrisch bestimmt werden.SummaryThe liquid-liquid extraction and precipitation of anionic complexes of transition metals employing selenonium salts are investigated. Triphenylselenonium dichromate, perchlorate and molybdate are advantageous because of their low solubility (the tungstate is easily soluble). [(C6H5)3Se]2Cr2O7 can be extracted quantitatively. [(C6H5)3Se]ClO4 is suitable for the detection of 5 μg of ClO4− in presence of high quantities of ClO3−. The liquid-liquid extraction of chromium as [(C6H5)3Se]2Cr2O7 allows the determination of 25 μg Cr in cast-iron and steels, containing manganese, vanadium and molybdenum. The cation [(C6H5)3Se]+ in selenonium compounds can be determined by precipitation as [(C6H5)3Se] [(C6H5)4B].
12 citations
TL;DR: In this paper, it was shown that 2.5 to 250 γ of mercury can be determined photometrically by extracting the mercury salt solution with an excess of dithizon solution in chloroform and measuring the extinctions of the chloroplast layer at 500 and 610 mμ.
Abstract: It is possible to determine 2.5 to 250 γ of mercury photometrically by extracting the mercury salt solution with an excess of dithizon solution in chloroform and measuring the extinctions of the chloroform layer at 500 and 610 mμ. The amount of mercury is calculated from the volume of dithizon solution used and the extinctions E500 and E610 measured, thus standardization of the dithizon solution is unnecessary.
The pure solution of the orange coloured mercury dithizonate in chloroform turns a dirty greenish orange in daylight, in direct sunlight it becomes bluish purple in a few minutes. The original colour is quickly recovered again in the dark. This reversible photochemical process is completely inhibited by acetic acid.
12 citations
12 citations
12 citations