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100 PSEUDOMORPHISM. is present, the glass is blood-red, and only becomes violet after the addition of tin. In order to discover oxide of titanium in titanic iron ore, the assay must be dissolved in hydrochloric acid, and the solution boiled with tin, by which it acquires the violet colour of oxide of titanium. Titanic iron-ore shows a blue colour when heated with concentrated sulphuric acid. For further information respecting the methods’ of distin guishing the constituents of minerals, the reader is referred to the treatises on the use of the blowpipe by Berzelius and Plattner, the introductions to Analytical Chemistry by Kam- meisberg and Eresenius, and IT. Kose’s ‘ Ausfiirliclies Hand- buch der Analytischen Chemie.’ Methods of discriminating mineral species by simple experiments with the blowpipe and with liquid tests are given in von Kobell’s ‘Tafeln zur Bestiin- mung der Mmeralien mittelst einfacher chemischer Versuche aul trockenem und nassem Wege.’ These tables have been translated into English by Muspratt. Pseudomorphism. 284. Pseudomorphous minerals are those which have the composition of one mineral and the form of another. Thus Steatite is found in the form of quartz, spinelle, idoerase, garnet, tourmaline, topaz, felspar ; malachite in the forms of chessy- Iite, towanite, fahlerz, cuprite; serpentine in the form of gar- ■* e s P' ne H R , augite, humite, olivine, amphibole; quartz in the form of baryte, fluor, calcite, dolomite, galena, scheelite, cerussite, hematite, pyrite, chalybite; chalcedony in the form oi datholite; mica, and the substances called hard fahlunite, aspasiolite, fahlunite, esmarkite, bonsdorffite, chlorophyllite, weissite, praseolite, pyrargyllite, gigantolite, pinite, in the form or cordiente. 1 or an account of the probable nature of the processes by which one mineral fills the space previously occupied by another, as one mineral is, without change of form, converted into another, or otherwise altered in its composition, the reader is referred to the Essays of Haidinger, in Poggendorff’s ‘ Anna- + eil Tn > 8 .' anc ^ b‘2, s. 161; and especially ‘ AT , 8 ' '^ ) * 0 P seu( iomorphosen des Mineralreichs,’ and -Nachtrag zu den Pseudomorphosen des Mineralreichs.’ An abstract of the latter has been given by Mr. Dana, in Silliman’s Journal for 1845, vol. xlviii., p. 66; and 1848, new series, vol. vi.,