libristo early american nature writers 4587798

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Ceramic Chemistry - 2876463755

150,73 zł

Ceramic Chemistry Read Books

Książki / Literatura obcojęzyczna

PREFACE. Modern Ceramics may be said to date from Brogniart 1770-1847. The predominance of the French chemists in the science of pottery during the early and middle parts of last century caused the word Ceramic to be transplanted into English and German. Seger and his colleagues then caused potters to turn their eyes to Berlin for a generation but there are not wanting signs that many of Seger s conclusions are being seriously questioned by the present school of ceramists. New vitality has sprung from the foundation of the American and English Ceramic Societies and from the adoption of the science as a subject for degrees in many American Universities. That Ceramics is suitable for University study both theoretical and practical there can be no doubt. It is the natural means of transition from Geology to Chemistry, Mathematics, Physics, and Engineering. No other subject unites those five sciences so intimately. If this book should promote the secondary and higher study of the subject in England, the writers aim will be accomplished. He wishes to express his indebtedness to the Transactions of the English and American Ceramic Societies. 292432 H. H. S. CERAMIC CHEMISTRY. v. CONTENTS. Page Preface ... . y Introduction Chapter. - - - . I. Geological Origins II. Clay III. Clay Analysis vii. - - - 1 - 12 - 17 IV. Raw Materials - 30 V. Bodies 37 VI. Glazes 46 VII. Enamels 52 VIII. The Production of Colour 59 IX. Firing of the Ware - X. Loss in Manufacture - - - 71 XI. Industrial Disease - - - 75 XII. Testing of Finished Ware - - - 79 XIII. Classification of Pottery XIV. Research - . ... XV. Bibliography in English Index of Authors - 65 84 - 82 - - 85 Index of Subjects 89 87 CERAMIC CHEMISTRY. vii. INTRODUCTION. Ceramic chemistry is concerned chiefly with the reactions of silicates. It is complicated by the difference in conduct between body and glaze. In the latter, if properly matured, the chemical reaction between the constituents has proceeded to a finish, and the melt consists of a homogeneous mixture or solid solution of silicates and, it majj be, borates and phosphates, and any eutectics that may be formed. With the body, on the other hand, it is different. The firing is only conducted to incipient vitrification, if as high as that. The chemical reactions are not allowed to proceed to a finish. The chemistry of pottery is therefore, as far as the body is concerned, one of incomplete reactions. Consequently, the nature and condition of the raw materials are of im- are irrelevant portance in the body, while in the glaze they as long as the same ultimate composition is preserved. CERAMIC CHAPTER I. GEOLOGICAL ORIGINS. The composition of the earths crust has been estimated by several observers, the latest being F. W. Clarke 1901, who based his calculations on 830 analyses of typical samples of the primary rocks, and found an average of Silica 59. 71 per cent. Alumina 15.41 ,, Ferric oxide 2 . 63 Ferrous oxide 3 .52 ,, Lime 4.90 Magnesia 4 . 36 ,, Potassium oxide 2 . 80 Sodium oxide 3 . 55 ,, Water of combination 1 .52 Titania 0.60 Phosphoric anhydride 0.22 ,, 99.22 per cent. Which leaves less than 1 per cent, for all other combinations of elements. Clarkes figures have the molecular formula Na2O 0.173 K2O 0.090 A1O 045 SiO2 3.0 aO 0.264 I F o 8 Oo49 Ti 2 022 I MgO 0.327 P2 5 0.005 FeO 0.146 J The melting point of such a mixture would be about 1,200 C. As the temperature of the earth, according to the figure adopted by the British Association, increases 1 C. for every 117ft. in depth, it follows that we have at least 25 miles of solid earth beneath us. Owing, however, to the pressure of the superincumbent strata, the melting point of the rocks is probably raised appreciably, but the depth given indicates a minimum limit. The specific gravity of the primary rocks of the earths crust is 2...

Sklep: Libristo.pl

Art on My Mind - 2873613377

77,37 zł

Art on My Mind The New Press

Książki / Literatura obcojęzyczna

Political theorist and critic hooks continues the work of Black Looks (not reviewed), exploring the politics of representation, aesthetics, and the place of the African-American woman artist. This collection of 18 essays in art criticism and five interviews with prominent black women artists is hooks's response to the paucity of African-American art critics, particularly women. Drawing effectively on her personal experience of art as both maker and viewer, hooks urges that we take art seriously as a focus for struggle, emphasizing its transformative power. At the same time, she eschews essentialist arguments that would reduce all black art to protest art, arguments that have repeatedly been narrowed to discussions of "good" and "bad" images. Instead, she calls for "a revolution in the way we see, the way we look." What is at stake here, she says, is nothing less than control over the representation of the self; she points to the empowering nature of personal photography as an example. The book itself is an odd creature. The first half is a rocky road full of academic artcrit jargon of the kind usually found in the pages of artforum (which is where one of these pieces first appeared), and the early dialogues, with Carrie Mae Weems and Alison Saar, are unsatisfying, with hooks dominating the conversations. But the second half of the book is a return to form for one of the most astute cultural and political writers in the country today. Essays on black vernacular architecture, representation of the black male body, and the creative process of women artists are powerful and concise, and the dialogues with Emma Amos, Margo Humphreys, and particularly LaVerne Wells-Bowie are a real contribution to our understanding of the situation of black women artists. It is impossible to imagine hooks writing a book devoid of interest, and the second half of this one is excellent indeed. (Kirkus Reviews)

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