DOCSLIB.ORG

Barium, Zinc and Strontium Yellows in Late 19Th–Early 20Th Century Oil Paintings Vanessa Otero1* , Marta F

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Barium, Zinc and Strontium Yellows in Late 19Th–Early 20Th Century Oil Paintings Vanessa Otero1* , Marta F Otero et al. Herit Sci (2017) 5:46 DOI 10.1186/s40494-017-0160-3 RESEARCH ARTICLE Open Access Barium, zinc and strontium yellows in late 19th–early 20th century oil paintings Vanessa Otero1* , Marta F. Campos1, Joana V. Pinto2, Márcia Vilarigues1, Leslie Carlyle1 and Maria João Melo1 Abstract This work focuses on the study of the 19th century yellow chromate pigments based on barium (BaCrO­ 4), zinc ­(4ZnCrO4 K2O 3H2O) and strontium ­(SrCrO4). These pigments, which are reported to shift in hue and darken, have been found· in· 19th century artworks. A better understanding of their historic manufacture will contribute to the visual/chemical interpretation of change in these colours. Research was carried out on the Winsor & Newton (W&N) 19th century archive database providing a unique insight into their manufacturing processes. One hundred and three production records were found, 69% for barium, 25% for zinc and 6% for strontium chromates, mainly under the names Lemon, Citron and Strontian Yellow, respectively. Analysis of the records shows that each pigment is charac- terised by only one synthetic pathway. The low number of records found for the production of strontium chromate suggests W&N was not selling this pigment formulation on a large scale. Furthermore, contrary to what the authors have discovered for W&N chrome yellow pigments, extenders were not added to these pigment formulations, most probably due to their lower tinting strength (TS). The latter was calculated in comparison to pure chrome yellow ­(PbCrO4, 100% TS) resulting in 92% for barium, 65% for zinc potassium and 78% for strontium chromate pigments. This indicates that W&N was probably using extenders primarily to adjust pigment properties and not necessarily as a means to reduce their costs. Pigment reconstructions following the main methods of synthesis were character- ised by complementary analytical techniques: Fibre optic refectance spectroscopy, X-ray difraction, micro-Raman and micro-Fourier transform infrared spectroscopies. These pigments can be clearly distinguished on the basis of 2 1 their infrared ­CrO4 − asymmetric stretching fngerprint profle (between 1000 and 700 cm− ) and of their Raman 2 1 ­CrO4 − stretching bands (850–950 cm− ). This enabled their identifcation in historic paint samples: a tube of late 19th century W&N Lemon Yellow oil paint and micro-samples from paintings by three Portuguese painters, António Silva Porto (1850–1893), João Marques de Oliveira (1853–1927) and Amadeo de Souza-Cardoso (1887–1918). The good cor- relation found between the reconstructions and historic samples validates their use as reference materials for future photochemical studies. Keywords: Barium yellow, Zinc yellow, Strontium yellow, Reconstructions, Winsor & Newton archive, 19th century paintings, µ-Raman, µ-FTIR, FORS, XRD Introduction zinc and strontium were introduced. While not as popu- Vauquelin’s discovery of chromium in 1797 and of the lar with artists, these three new yellows were nevertheless diferently coloured compounds derived from it, led to adopted throughout the 19th century [2–6]. Burnstock the development of a range of new yellow pigments, the et al. identifed these compounds in 19th to 20th cen- most popular being chrome yellow (lead chromate) [1]. tury pigments and paints using X-ray difraction (XRD) In addition, three yellow chromates based on barium, and scanning electron microscopy (SEM) with elemental analysis [6]. Tey are still in use today, especially as anti- *Correspondence: [email protected] corrosive pigments [7]. Table 1 includes their common 1 Department of Conservation and Restoration and LAQV‑REQUIMTE, and chemical names, chemical formula, colour index Faculty of Sciences and Technology, Universidade NOVA de Lisboa, (C.I.) numbers and other characteristics. 2829‑516 Monte da Caparica, Portugal Full list of author information is available at the end of the article © The Author(s) 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Otero et al. Herit Sci (2017) 5:46 Page 2 of 13 Table 1 Chrome, barium, zinc and strontium yellow pigments: common and chemical names, chemical formula, colour index number (C.I.), refractive index, solubility product constants (Ksp at 25 °C), crystal structure and space group [8–11] Common names Chrome yellow Barium yellow Zinc yellow Strontium yellow Lemon yellowa Citron yellow Strontian yellow Chemical name Lead chromate Barium chromate Zinc potassium chromate hydrate Strontium chromate Chemical formula PbCrO BaCrO 4ZnCrO K O 3H O SrCrO 4 4 4· 2 · 2 4 C.I. pigment yellow 34:77600 31:77103 36:77955 32:77839 Refractive index 2.3–2.65 1.94–1.98 1.84–1.9 1.92–2.01 14 10 11b 5 K 1.8 10− 1.17 10− 3.3 10− 3.5 10− sp × × × × Crystal structure Monoclinic Orthorhombic Monoclinic Monoclinic Space group P21/n Pnma P21/n P21/n a The designation “lemon yellow” was also used for zinc and strontium chromates [5] but herein it will only refer to barium chromate b The solubility product constant of zinc yellow is not tabulated. It was calculated using the data from Simonsen et al. [12] Barium chromate (BaCrO4), frst synthesised and ana- chromate (4ZnCrO4·K2O·3H2O) has been observed lysed by Vauquelin, resulted from adding a solution of in Georges Seurat’s paintings including A Sunday on barium nitrate to a chromate or dichromate (e.g. sodium La Grande Jatte—1884 [4, 17–19]. Casadio et al. stud- or potassium) solution [1]. Barium chloride may also be ied the darkening of oil paints prepared with a mod- used as an alternative source of barium [2, 13]. Trough- ern zinc yellow (DuPont, Y-539-D; PS-83109) and cold out the 19th century, barium chromate was known under pressed linseed oil (W&N), and subjected to artifcial several diferent names including: barium yellow, lemon aging under combined environmental conditions: light/ yellow, ultramarine yellow, baryta yellow and Steinbühl dark, air humidity (50 and 90% RH) and acidic gases yellow [2, 14]. (SO2 and CO2). Colour changes were observed in all Zinc chromate with the approximate composition of aging experiments, but the highest degree of darkening 4ZnCrO4·K2O·3H2O also appeared in the beginning of occurred in the presence of light, SO2 and 90% RH. By the 19th century, and the origin of its discovery is unclear means of Electron energy loss spectroscopy (EELS) and [1]. Recently, Simonsen et al. have determined its struc- X-ray absorption near-edge spectroscopy (XANES), ture as KZn2(CrO4)2H2O(OH) by single-crystal X-ray they determined that the darkening is related to the crystallography [12]. Tis pigment is formed by precipita- reduction of the original Cr(VI) in zinc yellow pigment tion when a solution of a zinc salt is added to a chromate to Cr(III) species such as the green chromium oxide solution (e.g. of sodium or potassium), in the presence (Cr2O3). Orange Cr(VI) dichromate species were also of potassium ions [2]. During the 19th century, the most detected in the samples aged under light, SO 2 and 50% common names for zinc chromate were zinc yellow and RH [17–19]. citron yellow but it was also labeled as ultramarine yel- low, yellow button of gold and permanent yellow [2, 5, The investigative methodology 14]. Te present study was prompted by the identifcation of It is also uncertain who synthesised strontium chro- barium and zinc chromate in oil paintings by the Portu- mate (SrCrO4) for the frst time [2, 14]. Presently it is guese Naturalists António Silva Porto (1850–1893) and obtained when a solution of strontium chloride is added João Marques de Oliveira (1853–1927), Fig. 1 (see also to a sodium dichromate solution [7]. During the 19th Additional fle 1: Figure S1) [20]. Strontium chromate century onwards, it appears variously as: strontian yellow, was also found in oil paintings by Silva Porto [20] and by strontaine yellow, lemon yellow and ultramarine yellow the Portuguese Modernist Amadeo de Souza-Cardoso (the last two names could also refer to barium chromate) (1887–1918), Fig. 2 [21]. Te study of the materials and [2, 5, 14]. techniques of these painters was carried out in the frame- Of the three yellow chromate pigments, barium work of the interdisciplinary project ‘Crossing Borders: chromate is considered the most lightfast, neverthe- History, materials and techniques of Portuguese painters less, it is reported to turn green after long exposure from 1850 to 1918 (Romanticism, Naturalism and Mod- to light [1]. Tis agrees with the reactivity model sug- ernism)’. Previously, Correia et al. had identifed barium gested by Monico and Tan et al., that relates the ten- and strontium chromate using μ-Raman in oil paintings dency to degrade with the solubility of the chromate by the Portuguese Naturalist Henrique Pousão (1859– pigments, see Table 1 [15, 16]. Darkening of zinc 1884) [22]. Otero et al. Herit Sci (2017) 5:46 Page 3 of 13 chemistry and characteristics of the reconstructed pig- ments were investigated using Fibre optic refectance spectroscopy (FORS), X-ray difraction (XRD), micro- Raman (μ-Raman) and micro-Fourier transform infra- red (μ-FTIR) spectroscopies. Teir composition was compared with samples from a late 19th century W&N “Lemon Yellow” tube of oil paint and late 19th-and early 20th century Portuguese oil paintings, Figs. 1 and 2.
Load more

Recommended publications
  • Preparation of Barium Strontium Titanate Powder from Citrate
    APPLIED ORGANOMETALLIC CHEMISTRY Appl. Organometal. Chem. 13, 383–397 (1999) Preparation of Barium Strontium Titanate Powder from Citrate Precursor Chen-Feng Kao* and Wein-Duo Yang Department of Chemical Engineering, National Cheng Kung University, Tainan, 70101, Taiwan TiCl4 or titanium isopropoxide reacted with INTRODUCTION citric acid to form a titanyl citrate precipitate. Barium strontium citrate solutions were then BaTiO3 is ferroelectric and piezoelectric and has added to the titanyl citrate reaction to form gels. extensive applications as an electronic material. It These gels were dried and calcined to (Ba,Sr)- can be used as a capacitor, thermistor, transducer, TiO3 powders. The gels and powders were accelerometer or degausser of colour television. characterized by DSC/TGA, IR, SEM and BaTiO3 doped with strontium retains its original XRD analyses. These results showed that, at characteristics but has a lower Curie temperature 500 °C, the gels decomposed to Ba,Sr carbonate for positive temperature coefficient devices under and TiO2, followed by the formation of (Ba,Sr)- various conditions. TiO3. The onset of perovskite formation oc- Besides solid-state reactions, chemical reactions curred at 600 °C, and was nearly complete at have also been used to prepare BaTiO3 powder. 1 1000 °C. Traces of SrCO3 were still present. Among them the hydrolysis of metal alkoxide , The cation ratios of the titanate powder oxalate precipitation in ethanol2, and alcoholic prepared in the pH range 5–6 were closest to dehydration of citrate solution3 are among the more the original stoichiometry. Only 0.1 mol% of the attractive methods. In 1956 Clabaugh et al.4 free cations remained in solution.
    [Show full text]
  • Derivation of Proposed 2007 Draft Matrix Soil Standards for Barium
    Derivation of Proposed 2007 Draft Matrix Soil Standards for Barium Glyn R. Fox Environmental Management Branch Environmental Protection Division September 24, 2007 Victoria, British Columbia Table of Contents Page 1. Introduction ……………………………………………………………………… 4 2. Details Related to Derivation of Proposed 2007 Draft Matrix Soil Standards 2.1 Derivation of Human Health Protection Standards – Intake of contaminated soil ………………………………………………………….. 7 2.2 Derivation of Human health Protection Standards – Groundwater used for drinking water ……………………………….…………….......... 7 2.3 Derivation of Environmental Protection Standards – Toxicity to soil invertebrates and plants ……………………………………….......... 9 2.4 Derivation of Environmental Protection Standards – Livestock ingesting soil and fodder ………………………………………………… 9 2.5 Derivation of Environmental Protection Standards – Major microbial function impairment ………………………………….……… 10 2.6 Derivation of Environmental Protection Standards – Groundwater flow to surface water used by aquatic life ..…………………………… 10 2.7 Derivation of Environmental Protection Standards – Groundwater used for livestock watering ……………………………………………… 11 2.8 Derivation of Environmental Protection Standards – Groundwater used for irrigation ………………………………………………………… 12 2.9 CSST “Background” Adjustment ……………………..……………… 12 2.10 Application of CSST Rounding-off Rule ……………………………… 12 3. References …….…………………………………………………………………… 13 2 Table of Contents (continued) Page 4. Exhibits Exhibit 1. Proposed 2007 Draft Matrix Soil Standards for Barium ……..… 19 5. Tables
    [Show full text]
  • PUBLIC HEALTH STATEMENT Cesium CAS#: 7440-46-2
    PUBLIC HEALTH STATEMENT Cesium CAS#: 7440-46-2 Division of Toxicology April 2004 This Public Health Statement is the summary exposed to a substance when you come in contact chapter from the Toxicological Profile for cesium. It with it. You may be exposed by breathing, eating, is one in a series of Public Health Statements about or drinking the substance, or by skin contact. If the hazardous substances and their health effects. A substance is radioactive, you may also be exposed shorter version, the ToxFAQs™, is also available. to radiation if you are near it. This information is important because this substance may harm you. The effects of exposure to External exposure to radiation may occur from any hazardous substance depend on the dose, the natural or man-made sources. Naturally occurring duration, how you are exposed, personal traits and sources of radiation are cosmic radiation from space habits, and whether other chemicals are present. For or radioactive materials in soil or building materials. more information, call the ATSDR Information Man-made sources of radioactive materials are Center at 1-888-422-8737. found in consumer products, industrial equipment, _____________________________________ atom bomb fallout, and to a smaller extent from This public health statement tells you about cesium hospital waste, medical devices, and nuclear and the effects of exposure. reactors. The Environmental Protection Agency (EPA) If you are exposed to cesium, many factors identifies the most serious hazardous waste sites in determine whether you’ll be harmed. These factors the nation. These sites make up the National include the dose (how much), the duration (how Priorities List (NPL) and are the sites targeted for long), and how you come in contact with it.
    [Show full text]
  • Of the Periodic Table
    of the Periodic Table teacher notes Give your students a visual introduction to the families of the periodic table! This product includes eight mini- posters, one for each of the element families on the main group of the periodic table: Alkali Metals, Alkaline Earth Metals, Boron/Aluminum Group (Icosagens), Carbon Group (Crystallogens), Nitrogen Group (Pnictogens), Oxygen Group (Chalcogens), Halogens, and Noble Gases. The mini-posters give overview information about the family as well as a visual of where on the periodic table the family is located and a diagram of an atom of that family highlighting the number of valence electrons. Also included is the student packet, which is broken into the eight families and asks for specific information that students will find on the mini-posters. The students are also directed to color each family with a specific color on the blank graphic organizer at the end of their packet and they go to the fantastic interactive table at www.periodictable.com to learn even more about the elements in each family. Furthermore, there is a section for students to conduct their own research on the element of hydrogen, which does not belong to a family. When I use this activity, I print two of each mini-poster in color (pages 8 through 15 of this file), laminate them, and lay them on a big table. I have students work in partners to read about each family, one at a time, and complete that section of the student packet (pages 16 through 21 of this file). When they finish, they bring the mini-poster back to the table for another group to use.
    [Show full text]
  • Barite (Barium)
    Barite (Barium) Chapter D of Critical Mineral Resources of the United States—Economic and Environmental Geology and Prospects for Future Supply Professional Paper 1802–D U.S. Department of the Interior U.S. Geological Survey Periodic Table of Elements 1A 8A 1 2 hydrogen helium 1.008 2A 3A 4A 5A 6A 7A 4.003 3 4 5 6 7 8 9 10 lithium beryllium boron carbon nitrogen oxygen fluorine neon 6.94 9.012 10.81 12.01 14.01 16.00 19.00 20.18 11 12 13 14 15 16 17 18 sodium magnesium aluminum silicon phosphorus sulfur chlorine argon 22.99 24.31 3B 4B 5B 6B 7B 8B 11B 12B 26.98 28.09 30.97 32.06 35.45 39.95 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton 39.10 40.08 44.96 47.88 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.39 69.72 72.64 74.92 78.96 79.90 83.79 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 85.47 87.62 88.91 91.22 92.91 95.96 (98) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3 55 56 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 cesium barium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon 132.9 137.3 178.5 180.9 183.9 186.2 190.2 192.2 195.1 197.0 200.5 204.4 207.2 209.0 (209) (210)(222) 87 88 104 105 106 107 108 109 110 111 112 113 114 115 116
    [Show full text]
  • Paediatric Barium Swallow/Meal Information for Parents and Carers Your Doctor Has Referred Your Child for a Barium Swallow/Meal to Look at Their Food Pipe and Stomach
    Oxford University Hospitals NHS Trust Paediatric Barium Swallow/Meal Information for parents and carers Your doctor has referred your child for a barium swallow/meal to look at their food pipe and stomach. We have written this information leaflet to help you and your child to understand this test. We hope it answers some of the questions you both may have and helps you and your child to feel more prepared and relaxed. page 2 What is a barium swallow/meal? A barium swallow/meal uses a special liquid to allow the X-ray doctor (radiologist) to see your child’s oesophagus (food pipe or gullet), stomach and the first part of their intestines using an X-ray camera. What does this test involve? Your child will be asked to drink a special drink called barium. This is a white liquid with a chalky texture. It is not radioactive but is used as it shows up well on X-ray images. Your child will need to drink the barium whilst lying on a couch with the X-ray camera over their tummy (about 75cm away). They may need to change position, so you will be asked to stay close to them at all times to make sure they are safe. If your child is able to, they will usually be asked to drink using a straw so that they can stay lying down. If they are not able to use a straw they can drink the barium from a bottle or beaker. If they are currently being fed through a nasogastric (NG) tube, we will use that to give them the barium.
    [Show full text]
  • A Model of Chromate Leaching from Inhibited Primers
    18th World IMACS / MODSIM Congress, Cairns, Australia 13-17 July 2009 http://mssanz.org.au/modsim09 A model of chromate leaching from inhibited primers Jenkins, D.R. 1 and A.D. Miller 2 1 CSIRO Mathematical and Information Sciences, Locked Bag 17, North Ryde NSW 1670 2 CSIRO Mathematical and Information Sciences, Private Bag No 2, Glen Osmond SA 5064 Email: [email protected] Abstract: We present a model of the production, transport and reaction of various ionic species involved in the process of leaching of chromate ions from primer layers on metal substrates. The polymer primer layers contain a range of filler particles, some of which are inert, while others are “active”, in the sense that they act to inhibit the onset and progression of corrosion in bare metal, in a situation where the primer layer is breached. A key active corrosion inhibitor is chromate ions, usually provided by strontium chromate (SrCrO4) particles in the primer. The chromate ions are formed by dissolution in water, which needs to penetrate the primer layer for this to occur. The ions then leach out to the damage site and react with the metal surface to inhibit corrosion. Unfortunately chromate is carcinogenic and therefore is now banned in various parts of the world. More acceptable alternatives for chromate are being keenly sought. A valuable aspect of chromate ions in their inhibitor role is their ability to relatively rapidly leach out after damage initiation, which is not true of many other inhibitors. However, aspects of the mechanism of chromate leaching through primer layers are not well understood.
    [Show full text]
  • Chemical-Specific Parameters Supporting Table May 2016 Analyte
    Regional Screening Level (RSL) Chemical-specific Parameters Supporting Table May 2016 Contaminant Molecular Weight Volatility Parameters Melting Point Density Diffusivity in Air and Water Partition Coefficients Water Solubility Tapwater Dermal Parameters H` (atm- Density Dia Diw Dia and Diw Kd Kd Koc log Kow S B τevent t* Kp 3 3 2 2 Analyte CAS No. MW MW Ref (unitless) m /mole) H` and HLC Ref VP VP Ref MP MP Ref (g/cm ) Density Ref (cm /s) (cm /s) Ref (L/kg) Ref (L/kg) Koc Ref (unitless) log Kow Ref (mg/L) S Ref (unitless) (hr/event) (hr) (cm/hr) K Ref Acephate 30560-19-1 1.8E+02 PHYSPRO 2.0E-11 5.0E-13 EPI 1.7E-06 PHYSPROP 8.8E+01 PHYSPROP 1.4E+00 CRC89 3.7E-02 8.0E-06 WATER9 1.0E+01 EPI -8.5E-01 PHYSPRO 8.2E+05 PHYSPROP 2.1E-04 1.1E+00 2.7E+00 4.0E-05 EPI Acetaldehyde 75-07-0 4.4E+01 PHYSPRO 2.7E-03 6.7E-05 PHYSPROP 9.0E+02 PHYSPROP -1.2E+02 PHYSPROP 7.8E-01 CRC89 1.3E-01 1.4E-05 WATER9 1.0E+00 EPI -3.4E-01 PHYSPRO 1.0E+06 PHYSPROP 1.3E-03 1.9E-01 4.5E-01 5.3E-04 EPI Acetochlor 34256-82-1 2.7E+02 PHYSPRO 9.1E-07 2.2E-08 PHYSPROP 2.8E-05 PHYSPROP 1.1E+01 PubChem 1.1E+00 PubChem 2.2E-02 5.6E-06 WATER9 3.0E+02 EPI 3.0E+00 PHYSPRO 2.2E+02 PHYSPROP 3.1E-02 3.4E+00 8.2E+00 5.0E-03 EPI Acetone 67-64-1 5.8E+01 PHYSPRO 1.4E-03 3.5E-05 PHYSPROP 2.3E+02 PHYSPROP -9.5E+01 PHYSPROP 7.8E-01 CRC89 1.1E-01 1.2E-05 WATER9 2.4E+00 EPI -2.4E-01 PHYSPRO 1.0E+06 PHYSPROP 1.5E-03 2.2E-01 5.3E-01 5.1E-04 EPI Acetone Cyanohydrin 75-86-5 8.5E+01 PHYSPRO 8.1E-08 2.0E-09 PHYSPROP 3.4E-01 PHYSPROP -1.9E+01 PHYSPROP 9.3E-01 CRC89 8.6E-02 1.0E-05 WATER9 1.0E+00
    [Show full text]
  • Strontium Chromate from Austria and France
    Strontium Chromate from Austria and France Investigation Nos. 731-TA-1422-1423 (Preliminary) Publication 4836 October 2018 U.S. International Trade Commission Washington, DC 20436 U.S. International Trade Commission COMMISSIONERS David S. Johanson, Chairman Irving A. Williamson Meredith M. Broadbent Rhonda K. Schmidtlein Jason E. Kearns Catherine DeFilippo Director of Operations Staff assigned Kristina Lara, Investigator Samantha DeCarlo, Industry Analyst Tana von Kessler Economist Jennifer Brinckhaus, Accountant KaDeadra McNealy, Statistician David Goldfine, Attorney Douglas Corkran, Supervisory Investigator Address all communications to Secretary to the Commission United States International Trade Commission Washington, DC 20436 U.S. International Trade Commission Washington, DC 20436 www.usitc.gov Strontium Chromate from Austria and France Investigation Nos. 731-TA-1422-1423 (Preliminary) Publication 4836 October 2018 CONTENTS Page ....................................................................................................................... 1 ........................................................................................................ 3 Introduction ................................................................................................................ I‐1 Background ................................................................................................................................ I‐1 Statutory criteria and organization of the report ....................................................................
    [Show full text]
  • DECOMPOSITION of MIXTURES of Strontlum CHROMATE and STRONTIUM CARBONATE
    PART V!. DECOMPOSITION OF MIXTURES OF STRONTlUM CHROMATE AND STRONTIUM CARBONATE. By V. T. Atlzaz~alealzd S. K. K. Jatkar. INTRBDUCTIQN. It has been shown in Part V (This Jo~trnal, 1938, ZlA, 159) that the decon~positionof strontium chromate indicated intermediate stages at 50, 66.6 and 75% clecomposition in conformity with our observations on the decomposition of calcium chromate (This Jownal, 1937, ZOA, 55-56). The stages corresponding- to 80 and 100% deconlposition could not be obtained in this case because of the lack of a suitable tube material which woulcl stand temperatures above 1450" in vacuum. While studying the decomposition of the mixtures of lime with calcium chromate (This Joz~mal, 21A, 119) two additional stages in the decomposition corresponding to 33.3 and 40% clecom- position were obtained, the composition of each stage being, respec- tively, identical with the acid-soluble portions from 66.6 and 75 % stages for plain chromate. The composition of the acid-soluble por- tion is thus an indication of the con~position of the intermediate stages obtained in the decomposition of the chromate when mixed with the corresponcling oxide. The difference in the behaviour of the con~poundsformed at the 50% stages for calcium and strontium chronlates towards acid has already been pointed out in Part V of this series. We thus get from 50% stage For strontium chromate, an acid-soluble compound 8Sr0 4Cr03 Cr,O, corresi~onclingto 33.3% decomposition, which though obtained otherwise in the decomposition of calcium chromate and its mixtures with lime, contained one mot of SrO less, ihile the corres- ponding stage in the decomposition of calcium chromate yields an acirl-soluble portion 10Ca0 6Cr0, Cr,O, A strontium compound corresponding to 33.370 stage was also obtained by treating the 66.6% stage with acid, the composition of which was 9Sr0 4Cr0, Cr,O,.
    [Show full text]
  • Toxicological Profile for Zinc
    TOXICOLOGICAL PROFILE FOR ZINC U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service Agency for Toxic Substances and Disease Registry August 2005 ZINC ii DISCLAIMER The use of company or product name(s) is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry. ZINC iii UPDATE STATEMENT A Toxicological Profile for Zinc, Draft for Public Comment was released in September 2003. This edition supersedes any previously released draft or final profile. Toxicological profiles are revised and republished as necessary. For information regarding the update status of previously released profiles, contact ATSDR at: Agency for Toxic Substances and Disease Registry Division of Toxicology/Toxicology Information Branch 1600 Clifton Road NE Mailstop F-32 Atlanta, Georgia 30333 ZINC vi *Legislative Background The toxicological profiles are developed in response to the Superfund Amendments and Reauthorization Act (SARA) of 1986 (Public law 99-499) which amended the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA or Superfund). This public law directed ATSDR to prepare toxicological profiles for hazardous substances most commonly found at facilities on the CERCLA National Priorities List and that pose the most significant potential threat to human health, as determined by ATSDR and the EPA. The availability of the revised priority list of 275 hazardous substances was announced in the Federal Register on November 17, 1997 (62 FR 61332). For prior versions of the list of substances, see Federal Register notices dated April 29, 1996 (61 FR 18744); April 17, 1987 (52 FR 12866); October 20, 1988 (53 FR 41280); October 26, 1989 (54 FR 43619); October 17, 1990 (55 FR 42067); October 17, 1991 (56 FR 52166); October 28, 1992 (57 FR 48801); and February 28, 1994 (59 FR 9486).
    [Show full text]
  • Massachusetts Chemical Fact Sheet
    Massachusetts Chemical Fact Sheet Hexavalent Chromium Table 1: HEXAVALENT CHROMIUM COMPOUNDS: Compounds SELECTED EXAMPLES* Compound Chemical Formula CAS # This fact sheet is part of a series of chemical fact sheets Ammonium chromate (NH ) Cr0 7788-98-9 developed by TURI to help Massachusetts companies, 4 2 4 community organizations and residents understand the Ammonium dichromate (NH4)2Cr2O7 7789-09-5 chemical’s use and health and environmental effects, as Barium chromate BaCrO4 10294-40-3 well as the availability of safer alternatives. tert-Butyl Chromate [(CH3)3CO]2CrO2 1189-85-1 Hexavalent chromium compounds are a toxic form of Calcium chromate CaCrO4 13765-19-0 chromium and are used in a variety of industrial processes Chromic acid H2CrO4 7738-94-5 and products. Chromium VI chloride CrCl6 14986-48-2 Hexavalent chromium compounds are human carcinogens, Chromic trioxide CrO3 1333-82-0 mutagens and developmental toxicants and are acutely Hexavalent chromium ion Cr6+ 18540-29-9 toxic. Non-hexavalent chromium compounds do not pose Lead chromate PbCrO4 7758-97-6 the same level of concern with regard to either chronic or Lead chromate oxide PbCrO4-PbO 8454-12-1 acute toxicity. Potassium chlorochromate KCrO3Cl 16037-50-6 Until 2011, all chromium compounds were treated as Potassium chromate K2CrO4 7789-00-6 a single category under TURA. Beginning with Potassium dichromate K Cr O 7778-50-9 reporting year 2012, hexavalent chromium 2 2 7 compounds are reportable under TURA as a Silver chromate Ag2CrO4 7784-01-2 separate category and are designated as a Higher Sodium chromate Na2CrO4 7775-11-3 Hazard Substance, which lowers the reporting Sodium dichromate 7789-12-0 threshold to 1,000 lb/year.
    [Show full text]