PART III

_THE TECHNOLOGY OF THE ELEMENTS_

XVII. THE INCANDESCENT MANTLE INDUSTRY--HISTORICAL AND GENERAL INTRODUCTION 265

XVIII. THE CHEMICAL TREATMENT OF MONAZITE 275

XIX. THE MANUFACTURE OF MANTLES FROM COTTON AND RAMIE 291

XX. ARTIFICIAL SILK--ITS PRODUCTION AND USE IN THE MANTLE INDUSTRY 301

XXI. OTHER TECHNOLOGICAL USES OF THE CERIUM AND YTTRIUM ELEMENTS, ZIRCONIUM AND THORIUM 313

XXII. THE INDUSTRIAL APPLICATIONS OF TITANIUM AND ITS COMPOUNDS 325

INDEX 342

TABLE OF ABBREVIATIONS EMPLOYED IN THE REFERENCES

_Abstr. Chem. Soc._ Abstracts in Journal of the Chemical Society.

_Amer. Chem. J._ American Chemical Journal.

_Amer. J. Sci._ American Journal of Science.

_Annalen_ Justus Liebig’s Annalen der Chemie.

_Ann. Chim. Phys._ Annales de Chimie et de Physique.

_Astrophys. J._ Astrophysical Journal.

_Ber._ Berichte der Deutschen chemischen Gesellschaft.

_Berz. Jahres._ Berzelius’ Jahresbericht über die Fortschritte der Chemie und Mineralogie.

_Bull. Imp. Inst._ Bulletin of the Imperial Institute.

_Bull. Soc. chim._ Bulletin de la Société chimique de France.

_Bull. Soc. franc. Min._ Bulletin de la Société française de Minéralogie.

_Bull. Soc. franc. Photog._ Bulletin de la Société française de Photographie.

_Bull. U. S. Geol. Survey_ Bulletin of the United States Geological Survey.

_Cass. Mag._ Cassier’s Magazine.

_Centr. Min._ Centralblatt für Mineralogie, Geologie und Paläontologie.

_Chem. Eng._ Chemical Engineer.

_Chem. Ind._ Chemische Industrie.

_Chem. News_ Chemical News.

_Chem. Zeitg._ Chemiker Zeitung.

_Chem. Zentr._ Chemisches Zentralblatt.

_Compt. rend._ Comptes rendus hebdomadaires des Séances de l’Académie des Sciences.

_Dingl. Polyt. J._ Dingler’s Polytechnisches Journal.

_D. R. P._ Deutsche Reichspatentschrift.

_E._ English Patent Specification.

_Elect. chem. Ind._ Electrochemical Industry (since 1904, Electrochemical and Metallurgical Industry).

_F._ Brevet d’Invention de la République Française.

_J. Amer. Chem. Soc._ Journal of the American Chemical Society.

_J. Gasbel._ Journal für Gasbeleuchtung.

_J. Gaslighting_ Journal of Gaslighting.

_J. Ind. Eng. Chem._ Journal of Industrial and Engineering Chemistry.

_J. pr. Chem._ Journal für practische Chemie.

_J. Russ. Phys. Chem. Soc._ Journal of the Physical and Chemical Society of Russia.

_J. Soc. Chem. Ind._ Journal of the Society of Chemical Industry.

_Met. Chem. Eng._ Metallurgical and Chemical Engineering.

_Min. Mag._ Mineralogical Magazine and Journal of the Mineralogical Society.

_Monats._ Monatshefte für Chemie und verwandte Theile anderer Wissenschaften.

_Phil. Mag._ Philosophical Magazine.

_Phil. Trans._ Philosophical Transactions of the Royal Society of London.

_Pogg. Ann._ Poggendorff’s Annalen der Physik und Chemie.

_Proc. Amer. Acad._ Proceedings of the American Academy.

_Proc. Chem. Soc._ Proceedings of the Chemical Society.

_Proc. Roy. Soc._ Proceedings of the Royal Society.

_Prog. Age_ Progressive Age (now Gas Age).

_Publ. Astrophys. Observ. Publikationen des Astrophysikalischen Potsdam_ Observatoriums zu Potsdam.

_Schweigg._ J. Schweigger’s Journal für Chemie und Physik.

_Sitzungsber. kaiserl. Akad. Sitzungsberichte der kaiserlich Akademie Wiss. Wien_ der Wissenschaften zu Wien.

_Sitzungsber. königl. Akad. Sitzungsberichte der königlich Akademie Preussischen Wiss. Berlin_ der Wissenschaften zu Berlin.

_Stahl Eisen_ Stahl und Eisen.

_Trans. Amer. El. chem. Soc._ Transactions of the American Electrochemical Society.

_Trans. Amer. Inst. Min. Transactions of the American Institute Eng._ of Mining Engineers.

_Trans. Chem. Soc._ Transactions of the Chemical Society.

_Tsch. Min. Mitt._ Tschermak’s Mineralogische Mittheilungen.

_U. S. Geol. Survey_ United States Geological Survey--Mineral Resources of the United States.

_U. S. P._ United States Patent Specification.

_Zeitsch. anal. Chem._ Zeitschrift für analytische Chemie.

_Zeitsch. angew. Chem._ Zeitschrift für angewandte Chemie.

_Zeitsch. anorg. Chem._ Zeitschrift für anorganische Chemie.

_Zeitsch. Elektrochem._ Zeitschrift für Elektrochemie.

_Zeitsch. Kryst. Min._ Zeitschrift für Krystallographie und Mineralogie.

_Zeitsch. physikal. Chem._ Zeitschrift für physikalische Chemie, Stöchiometrie und Verwandtschaftslehre.

_Zeitsch. pr. Geol._ Zeitschrift für praktische Geologie.

_Zeitsch. wiss. Photochem._ Zeitschrift für wissenschaftliche Photographie, Photophysik und Photochemie.

INTRODUCTION

By SIR WILLIAM CROOKES, O.M., F.E.S.

The mysterious group of substances to which have been given the title of “rare earths” has long been the subject of my special study, and no one knows better the magnitude of the difficulties encountered in the investigation, or realises more clearly the comparative insignificance of the knowledge we have acquired. The rare earths constitute the most striking example of the association of chemical substances with others which are closely allied to themselves, and from which they are separable only with extreme difficulty. They form a group to themselves, sharply demarcated from the other elements, and it is my belief that by following the study of them to the utmost limits, we may arrive at the explanation of what the chemical elements really are and how they originated, and discover the reasons for their properties and mutual relations. When this knowledge has been wrested from Nature chemistry will be established upon an entirely new basis. We shall be set free from the need for experiment, knowing _a priori_ what the result of each and every experiment must be; and our knowledge then will as much transcend our present scientific systems as the knowledge of the skilled mathematician of the present day exceeds that of primitive man, counting upon his fingers. The great problem of the nature and genesis of the elements is approaching solution, and when the consummation is reached it will undoubtedly be found that the study of the rare earths has been an important factor in bringing it about.

There has long been a need for a work in the English language dealing historically and descriptively with these substances, and Mr. Levy’s book is well fitted to fill the gap. The chapters on the technical applications of the rare earths are particularly valuable, and the chemical aspect of the incandescent lighting industry is admirably treated. The author is to be congratulated upon having successfully achieved an important and useful piece of work.

WILLIAM CROOKES.

_December 1914._

THE RARE EARTHS