File:Annual report of the Regents (1900) (14778896252).jpg

Identifier: annualreportof5421900newy (find matches)
Title: Annual report of the Regents
Year: 1889 (1880s)
Authors: New York State Museum University of the State of New York. Board of Regents
Subjects: New York State Museum Science
Publisher: Albany : J.B. Lyon, State Printer
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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d light. The proportion of fluxes is greater in porcelain than in whiteearthenware; but still, taking porcelains as a whole, there is a widerange in their composition, as will be seen from the followingfigures representing the range of the ingredients used in the manu-facture of hard porcelains. (Hecht.- Dammer, Chem. Tech.1 :773 and following .) Per cent Olay substance 40-66 Quartz 12-40 Feldspar 15-30 Carbonate of lime (at times) , . 6 The variation outside of these limits should be ver^^ small, for ifthe clay substance gets below 40^, the refractoriness decreases con-siderably, as does also the ability of the ware to withstand suddenchanges of temperature. As excessive shrinkage in burning tends to cause cracking andwarping, one aim of ceramic chemists has been to produce bodies oflow shrinkage; and experiments have indicated that the use ofporcelain sherds ground up gives a much more homogeneous massthan can be obtained by the use of quartz. (Chemihei^ zeitung.1895. p. 89) be o 0^
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