398 J. W: Mallet on Sipylite, a new Niobate. 
The color of the mineral in mass is brownish black, in thin 
splinters a red brown, like that of dark pine-rosin ; one or two 
small specimens display a gradual passage to a brownish orange, 
and even a yellow, but whether in these cases the chemical 
Iiebvprcia tices remains quite the same, there is not sufficient 
material to determine. The streak is light cinnamon-brown to 
pale gray. The luster resinous and pseudo-metallic. In 
general appearance to the eye the mineral is much like fer- 
gusonite from Greenland, euxenite from the neighborhood of 
Arendal, and samarskite from North Carolina, save that the 
last named is more distinetly pitchy blac ‘ranslucent in 
thin splinters. Hardness = nearly 6. Specific gravity may 
be considered = 4°89; one specimen gave 4°887 at 12°5 C.; 
another 4892 at 17°°5. 
Heated alone in the ordinary blowpipe flame the mineral 
before which a stout blowpipe wire of splot readily melts to 
a bead, thin splinters are fused merely on the edges. Heated 
in a close glass tube, the same decrepitation, glowing and 
change of color are observed, and water is given off, which 
condensing on the surface of the tube is found to have an acid 
reaction, and slightly etches the glass. Fused with borax in 
the oxidizing flame, the mineral is dissolved, producing a 
yellow glass, which becomes pale on cooling, and assumes a 
greener tint in the reducing flame. With microcosmic salt, a 
yellowish green glass is obtained. Strong boiling hydrochloric 
acid attacks to some extent the mineral in fine powder, and the 
partial solution, if boiled with metallic tin and diluted with 
water, gives the fine sapphire-blue color due to niobium. This 
— hydrochloric acid solution, if diluted, contains zireonium 
nough to brown turmeric paper to an extent quite sensible if a 
Sinai experiment be made with similarly diluted hydro- 
chloric acid alone. Boiling concentrated sulphuric acid decom- 
ses the mineral completely, though somewhat slowly ; and the 
diluted solution gives a blue color on addition of metallic zine. 
e chemical analysis was made, with much care an 
patience, under my direction by Mr. W. G. Brown, a student in 
this laboratory during the last winter. The details of the 
method used are given in a notice of his work in the Chemical 
News. Tantalum was found to be present, but in such small 
quantity, certainly less than one-twelfth of the niobium, that a 
satisfactory separation could not be obtained by Marignac’ s 
meth The sp. gr. of the mixed niobic and tantalic oxides 
