II. MINERALS, ETC. 747 



3454. Instruments of Observation. 



Three prisms for demonstrating the different dispersions of 



axes in crystals. 



Tourmalin pincers (Tourmalin or Lyncurium). 

 Andalusite pincers. 



Prism of dense flint ; Rossette substance. 

 Dichroismal lens. 



M. Werlein, Paris. 



II. COLLECTIONS OF MINERALS, DIAGRAMS, 



MODELS OF CRYSTALS, &c. 



a. ROCKS AND MINERALS. 



3455. Microscopic Sections of rocks and minerals. 



J. R. Gregory. 



3456. "Explorer's Comparison Mineralogical Cabi- 

 net." J- R. Gregory. 



3457. Rough Gems and Precious Stones, in their natural 

 form and condition, 15 varieties; useful to travellers for the 

 purpose of comparison and testing. Thomas J. Downing. 



3458. Specimens of transparent slices of various Minerals 

 for the Microscope. 



Royal Polytechnic School at Delft, Prof. S. Bosscha. 



a. Specimens of minerals described in Prof. Vogelsang's work, " Die 

 Philosophic der Geologie," Bonn, 1867, and depicted on Tables I. and HI. 



b. Specimens of crystallites described in " Archives Neerlandaises des 

 Sciences Physiques et Naturelles," and depicted in Table VII. of Vol. V., and 

 Table III. of Vol. VI., and in Prof. Vogelsang's posthumous work, Die 

 Kristalliten," edited by Prof. F. Zirkel, Bonn, 1875. 



c. Quartz slices with cavities containing fluid carbonic acid. 



3459. Thin Sections of Minerals. 



Ludwig Holier, Giessen. 



3460. Collection of rare and remarkable specimens of Zinc 

 Ores from the north of Spain, and from the county Tipperary, 

 Ireland, to illustrate the modes of occurrence and formation of 

 hydrated silicates and carbonates, particularly the oolitic and imi- 

 tative forms. Professor Jos. P. O'Reilly, Dublin. 



3461. Photographs (4) of imitative shapes presented by 

 certain hydrated silicates and carbonates of Zinc in the collection 

 from the north of Spain. Professor Jos. P. O'Reilly, Dublin. 



3462. Sections or Diagrams illustrative of Zinc Ore de- 

 posits of silver mines, county Tipperary, Ireland. 



Professor Jos. P. O'Reilly, Dublin. 



