364 W. T. Repper—Pseudomorph after Anorthite. 
have not yet succeeded in isolating this yellow coloring matter 
unchanged, in order to test its effect on the accuracy of the 
iodine process or Lowenthal’s method. 
As to rown-red obtained from the fresh hemlock, it 
seems to belong to a different class of substances. It is pre- 
cipitated by gelatine, is acted on by iodine, is precipitated by 
antimony, and on fusion with potassium hydrate it is decom- 
pene and a substance is formed which blackens the iron stripe 
ike tannin. We have not yet obtained a sufficient quantity to 
determine its composition or to deduce a theory for its relation 
to di-gallic acid. Our experiments go to show that the red- 
brown is decomposed in the slow process of fermentation, and 
the iron-blackening substance thus formed may possibly be 
the agent of the tanning. 
Massachusetts Institute of Technology, Woman’s Laboratory, August, 1878. 
Art. XLIV.—On a Pseudomorph after Anorthite, from Franklin, 
New Jersey ; by Professor W. T. Ra@pPer. 
On the northern part of Mine Hill, at Franklin, New Jersey, 
there are found, partly in detached pieces scattered over the 
surface, or in the fences surrounding the fields of the miners, 
and in place in a stratum of white crystalline limestone, pseudo- 
morphs that have the form of anorthite, accompanied by a dark 
hornblende, and numerous small, very brilliant and highly 
modified, clove-brown crystals of sphene. The outside of the 
anorthite crystals, the larger of which are generally more or less 
cavernous, is invariably “candied” over by exceedingly small, 
brilliant prismatic crystals. ; 
e crystals, from one-eighth to two or three inches in size, 
are distinctly feldspathic in habit, the prevailing faces, in the 
rder of their dominancy, being: 0, 7-4, J 2-7,2-7and1. Owing 
to the above mentioned micro-crystalline character of the surface 
and consequent want of reflection, the angles can be measur 
only with the application-goniometer. The following angles 
are averages of a number of tolerably concordant measurements: 
OAt-i over 24 % 85°33’, — difference of extremes, 20’ 
OAT $114 32, “ é 12’ 
OAl $ 110 32, «“ «“ 5 
OA24 % 98 56, s os) ge 
LAr 120 50 
OA2'4 133 10, 
Onl 122 
OAi+ however is in some crystals as high as 88°. Cleavage 
O and 7-7 easy and distinct, generally dull, but the basal cleav- 
age occasionally sub-pearly. 
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