50 BULLETIN 42, UNITED STATES NATIONAL MUSEUM. 



Per cent. 



Aliimiua (AUOO 4.74 



Oxide of ziuc (ZuO) .* 13.75 



Lime (CaO)... 23.005 



Oxide of lead (PbO) 1. 556 



Sulphur ( S) 1.12 



(2) (51083): Showiuj;- hladed ciystals of tliii followiiiij; composition: 



Per cent. 



Silica ( SiOo) 34. 51 



Protoxide of irou (FeO)" 32.08 



Protoxide of manganese (MiiO) 4. 56 



Alumina (AljO.i) not determined 



Lime (CaO) 16.28 



Oxide of zinc (ZnO) 6.97 



Sulphur (S) 2.06 



Oxide of lead (PbO) 1.74 



(3) (51084) : Showing confused bladed crystals of the following composition : 



Per cent. 



Silica (SiOj) 35.65 



Protoxide of iron (FeO) t 31.68 



Protoxide of manganese (MnO) 2.07 



Alumina (AljO^) 3. .^)5 



Oxide of zinc (ZnO) 7.55 



Lime (CaO) 17.91 



Oxide of lead (PbO) , 1.47 



Sulphur (S) 1.60 



(4) (51085): Showing thick rhombohedial crystals of the following composition : 



Per cent. 



Silica (SiO,) 36.00 



Protoxide of iron (FeO) t 23.66 



Protoxide of luangaiiese (MnO) 1. 05 



Alumina (AI.2O3) not determined 



Lime (CaO) 25.70 



Oxide of zinc (ZnO) 9.00 



Oxide of lead (PbO) 1.71 



Sulphur (S) 1..33 



(5) (51086): Showing crystals in sheaves of the following composition : 



Per cent. 



Silica ( SiOi) 35. 62 



Protoxide of iron (FeO)v^ 26. 20 



Protoxide of manganese (MnO) 8. 91 



Alumina (AlsO,) 3.83 



Oxide of zinc (ZnO) 5. 57 



Lime (CaO) 17.90 



Oxide of lead (PbO) 1.53 



Sulphur (S) 1.61 



(6) Short, thick, prismatic crystals. (51088.) 



The following five specimens, the analyses of which weje made by 

 Mr. A. S. Dwight, m. e,, represent the impure slags or those which 



* Iron (Fe) 24. 95. t Iron (Fe) 18. 41. 



+ Iron (Fe) 24.64 per cent. \S Iron (Fe) 20.38 per cent. 



