204 BULLETIN 42, UNITED STATES NATIONAL MUSEUM. 



sample of these four sizes, aualyzed by Mr. J. A. Allen in the laboratory of the depart- 

 ment, gave : 



Per cent. 



Water (H.^O) l.:i^> 



Silica (810.2 ) 5.54 



Alumina (Al^O;,) 56.15 



Titautic acid (TiO,) 4.75 



Sesquioxide of iron ( i'ciO;i) 19. 8'2 



Protoxide of iron (FcO) .. . 9. 17 



Oxide of manganese ( .MuO) 0. 38 



Lime (CaO) 0.14 



Magnesia (MgO) '2.17 



99. 42 



Turkey emery and the coiuuiercial sizes grouiul from it, arc repre- 

 sented bj' twenty-three specimens from the Union Stone Company, Bos- 

 ton, Massachusetts. 



(1) 

 (2) 

 (3) 



(4) 

 (5) 

 (6) 

 (7) 

 (») 

 (9) 

 (10) 



(11) 

 (12) 



Lump, two speci 

 Ground, size 10. 

 Ground, size 12. 

 Ground, s'ze 14. 

 Ground, size 16. 

 Ground, size 18. 

 Ground, size 20. 

 Ground, size 24. 

 Ground, size 30. 

 Ground, size 36. 

 Ground, size 40. 

 Ground, size 46. 



mens. (.55885.) 

 (55865.) 

 (558G4.) 

 (55863.) 

 (55862.) 

 (.55861.) 

 (5.5860.) . 

 (55859.) 

 (55858.) 

 (5.5857.) 

 (558.56.) 

 (55855.) 



(13) 

 (14) 

 (15) 

 (16) 

 (17) 

 (18) 

 (19) 

 (20) 

 (21) 

 (22) 

 (23) 



Ground, 

 Ground, 

 Ground, 

 (xround, 

 Ground, 

 Ground, 

 Ground, 

 Ground, 

 Ground, 

 Ground, 

 Ground, 



size 54. 

 size 60. 

 size 70. 

 size 80. 

 size 90. 

 size 100. 

 size 120. 

 size F. 

 size 2F. 

 size 3F. 

 size 4F. 



(55854.) 

 (55«53.) 

 (55852.) 

 (55851.) 

 (55850.) 

 (55849.) 

 (5.584b.) 

 (55847.) 

 (55846.) 

 (55845.) 

 (.55844.) 



QUAHTZ. 



Massive quartz from North Carolina and the commercial sizes ground 

 from it, are represented by nine specimens from the Union Stone Com- 

 pany, Boston, Massachusetts. 



(1) Lump. (55887.) 



(2) Ground, size 4. (.55883.) 



(3) Ground, size 3. (.55882.) 



(4) Ground, size 2^. (55881.) 

 (5} Ground, size 2. (.5.5880. ) 



(0) Ground, size U. (5.5879.) 



(7) Ground, size 1. (.5.^878.) 



(8) Ground, size ^. (55877.) 



(9) Ground, size 0. (55884.) 



TRIPOLI. 



Tripoli cousistsof the siliceous shells of diatoms, and is therefore classed 

 with quartz. It often forms thick deposits of sand which have simply 

 to be washed to prepare it for a polishing powder. Large amounts of 

 it are used for this purpose. 



(1) Crude, from the mines of the St. 

 Louis Tripoli Company, Missouri. 

 Two specimens. (55028.) 



(2) Prepared. (55029.) 



(3) Prepared. (51231.) 



(4) Prepared. (51232.) 



