C. U. Shepard, Sr.—Mineralogical Contributions. 93 
conducted to complete saturation, producing no precipitate, 
whereby the absence of tantalic acid was inferred.* 
Analysis, the decomposition being effected by fusion with 
potash, gave the composition as follows: 
tallic acids 78°30 
Protoxyd of Iro 13°86 
Protoxyd'ot Manganese -.. 2-2. +... - 7°72 
Tin only in traces. 
100°28 
In two processes for the metallic acids, one by the decom- 
position of the mineral by sulphuric acid, ‘the other by potash, 
an exact agreement in specific gravity was found, viz.: 4-06; 
from which, perhaps, it may be just also to infer the absence of 
tantalic acid, whose density when pure, though varying some 
what according to its mode of preparation, averages fully one- 
third higher than the present result. 
Hermann distinguishes three varieties of columbite, 
(1) with gravity sores 5-9, (2) with gravity 55 to 5°9, aaa (3) 
with gravity 54; but it is very doubtful whether an example 
of the mineral under notice has ever fallen into his hands, as 
this locality is of recent discovery. In conclusion, it may be 
added that minute coa of uranochre were observed in 
patches and s cor upon a few of the crystals ; though no 
phen one the presence of uranium was afforded in the 
minera 
2. Unknown mineral (microlite ?) in Haddam columbite. 
This mineral I suspect to be new. It has never fallen under 
my notice until found among the productions of a recent blast- 
* The following reactions were obtained i in testing a solution of the above com- 
soda with th 
hag seep maid of mercury, a , dense 
precipitate of a ae yellowish white, w! ich after fifteen minutes assumed a green 
standing; fe: rrocyanid of potassium, no change at first, b 
one rwards; : 8 eae oric acid rendered the solution feebly oats at dee end of 
es immediate 
o hours; reci 
infusion of nut-galls no effect until a aed fe! hydrochloric acid was added, when a 
, orange-red precipitate appeared; nitric acid gave an abundant precipitate 
that did not dissolve bet Aaron etcoahion’s sparen oluminous ‘pre- 
: of the solution was evaporated to 4th i 
in porcelain, it e Town, black. i ficcacton reactions are 
those heretofore supposed to 0) umbium ; 
but it oo that they may be shared to some extent by those of the allied 
