New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1874-05-25

greater purity and beauty thpn that introduced into
the market under the nape of Rosensties or Cassel
green. Az result, ne recommends different
method aud calls attention to superior blue-gTeen
In regard to the two methods OK pre-
paration already published, he states that the one
by fusion of caustic baryta with pyroiusite and
chlorate Of potash affords n more beautiful anu
homogeneous product than that by ignition oil III
trate of baryta with sesqui-oxde or bihoxide OF
manganese and also that the color by the latter is
by no means as permanent, on account OF the reduc
ing action in time of traces of nitrous ACID reInan
ing. He found, however, better method in the ad-
dition Of chloride of barium to green boring soiu
ton Of manganate of potash, by which heaVy'
granular. though not crystalline precipltate is
formed Of violct-alm0st blue-color, when can
be toerably well washed by decantation, and hnany
be easily drained on filter. This loses color on
drying, by gradually increasing the temperature
until at the lowest redheat it appears nearly WHITE
with a trace of grayish blue By heating it higher
with access of air, in oXdizng flame, 1t gradu
ally becomes perfectly green, and by heating stiI
further passes to a beautiful green-blue, until
finally at high temperature, it forms dirty gray
isl-brown mass by reduction Of the manganlc acid'
With solution of permanganate OF potash, chiorluc
of barium affords, after continued boiling peach-
blossom-colored precipitate while the liquid retains
an intense violet color. This preciptate OF peran-
ganate of baryta can be washed by decartation ana
dried at 2l2o without changing color. with
gradual elevation of the temperature, however, 1t
loses color, but, unlike the manganate, does not
afford either blue or green compound Dy SIMPLY
heating with access OF AR on the contrary IL
rapidly passes into the gTaylsl-broWn compound ne
fore mentioned; so that the perinanganate, under
these conditions is not adapted to the preparation
of baryta-green. While the pigment produced Dy
ignition of the marganate suIpasSeS i'll beauty that
produced by the other two methods, and although III
micht be possible to improve that produced from inc
nitrate Of baryta, by manufacturing 1t In a re-
verbeTatOry furnace under strong oNld ng name,
in no case is the green equal Ill beauty 10 tne bc-
preen-amOst azure bue-cOmpound, OF which no
public notice has been taken. inns pigment mas dlI-
ferent shades according to the mode OF prcparation
some being almost pure blue, with slght uhge OF
green. and resembling the light blue color OF me
wing feathers OF some parrots deepening inc shaue
of green in the pigment strengthens the Color Dut
TO she same degree lmpairS Its neneSS, although III
will still surpass in beauty the pure green manganae
The formation of the buc-green compound depends
entirely on the alkalinity of the mass, but III Is
doubtful whether definite composition c0IreapondS
to each color, the temperature twhich snoald
never exceed briglt-red heat has greatly lnuu-
enced the color. Ii is at least certain that the man
ganate, as well as peTmanganaGo OF Daryta mixed
with about 20 per cent OF hydrate OF Daryta, VIII
always yield the bluegeen pigment on ignition.
The bue-green color depends entirely upon ITS base
character, since il first turns green and Is tncn
gradually decompOsed when the powder Is placed IN
weak acids. Baryta pigments are otherwise quite
permanent and tOleTably strong suphurc acld docs
not affect them for hours, at ordinary temperatures
and boiling potash has practically no effect on tue
green. In any the permanence OF the blue color
Is increased by addition of httle baryta. these
pigments seem particularly adapted to iresco-pant-
ing as they appear most brilliant on stone, and
especially on lime; but their preparation is rather
expensive.