576 PROCEEDINGS OF THE NEW YORK MEETING 



treatment of them and in the recognition of their work. He was also 

 a liberal assistant of other investigators, whom he helped by advice or by 

 contributions of analytical or of other determinative work. 



In 1898 he published a revised and almost completely re-written edition 

 of the Manual of Determinative Mineralogy and Blowpipe Analysis, 

 originally the work of Professor George J. Brush. The list of publica- 

 tions include over eighty titles, all of which are distinct contributions to 

 the science of mineralogy or chemistry. Their value consists in part in 

 being determinations of new species ; in part in being corrections based on 

 more exact analyses of numerous species whose composition had been pre- 

 viously imperfectly and unsatisfactorily determined. Of the entirely 

 new mineral species which were described by him, there are fourteen, 

 namely, bixbyite, canfieldite, clinohedrite, gerhardtite, glaucochroite, 

 graftonite, hamlinite, hancockite, leucophcenicite, nasonite, nesquehonite, 

 pearceite, roeblingite, and spangolite. There are twenty-one species whose 

 correct composition he was able to establish : alurgite, amblygonite, 

 argyrodite, aurichalcite, childrenite, chondrodite, clinohumite, connellite, 

 cookeite, ganomalite, hanksite, herderite, howlite, humite, monazite, ral- 

 stonite, staurolite, sulphohalite, topaz, tourmaline, and turquois. 



His last investigative work, which was being carried on in association 

 with Mr F. S. Stanley, was aimed at the elucidation of the problem 

 of the composition of the amphiboles. 



Among his specific achievements may be mentioned the recognition of 

 the isomorphic role played b}'- fluorine and hydroxyl in the structure of 

 numerous minerals and the consequent necessity for their recognition in 

 the composition and formula of such minerals ; also the determination of 

 the relations between the proportions of these constituents in a mineral 

 series and the physical properties of the minerals, as in topaz and in the 

 members of the humite group — humite, chondrodite, and clinohumite. 



Another important achievement was the recognition of germanium in 

 a silver ore from Bolivia and the correct crystallographic determination 

 of the mineral argyrodite, in which the element was first discovered ; also 

 the demonstration of the control exerted upon the character of the 

 crystal symmetry in such a chemically complex mineral as tourmaline by 

 the acid portion of the molecule, which appears to be largely independent 

 of the nature of the bases combined with the acid. 



His contributions to crystallography consist not only of numerous 

 accurate determinations and descriptions of crystal forms, but in the 

 elaboration of graphical methods of representing crystals and of calculat- 

 ing angular relationships and also in devising simple drawing instruments 

 and maps for use in spherical projection. His studies in these methods 



