Northern tribune. [volume] (Cheboygan, Mich.) 1875-1885, 1884-05-22

Ihe object OF type-ctch1ng ID 70 pro-
cure a plate of copper from which an
etching may at once be printed of, pre-
senting an exact fac-simile of any given
fine drawing. The method by which
this end is obtained is as follows: A brass
plate is taken of the size required, and
about a fifth of an inch thick, and n
side of this plate is polished smooth and
made black with nitrate of silver. The
rough side of this plate is then held over
q hot flame, and a preparation of wax
quite white and Opaque is melted onto
the blackened and smooth surface of the
brass plate until the whole is covered
and looks like a very thin, fiat and rec
tilinear cake covered with tho whitest
and levelest possible coating of sugar.
The artist then takes al etcfing-needle
and draws in little burrows on the wax,
which in every case must go down to the
black surface, q copy Of the picture
which is to be initiated, or as the case
may be, an original drawing of his own,
each line appearing quite black against
the wax. The drawing finished, the
artist-in this case, strangely enough, a
man who is both deaf and dumb,
but, notwithstanding this afiiction, an
excellent and trusted workman-takes
up a curious little instrument about the
size of a teaspoon, but having at its end
instead of q bowl, a miniature kettle
filed with melted wax, out of which,
pouring the liquid in the smallest drops,
he gradually builds up a comparatively
high table-land of wax over every por-
ton of the surface which has not been
furrowed with the etching-needle. This
Is a most delicate proceeding, and it
seems certain that the deaf and dumb
workman must make a mistake and owe
up some of his burrows. With the
greatest skill, however, he coasts round
svery little irregularity of the drawing,
and in no long time has the form COM
pletely built up and ready, as far as its
shape is concerned, to receive the coat
Of copper which electricity is ultimately
TO attach to it, and from which future
impressions may be taken. Before,
however, the copper a be applied,
three further processes must be gone
through. First, the waxen matrix must
be singed. A flame is rapidly passed
across it hither and thither, and this
slight melting runs the wax down
wherever it is near the exposed metal to
the very verge OF the lines, so that
no space is left uncovered except that
occupied by the actual strokes of the
drawing. This effect of the singeing If
almost miraculous, and greatly sur.
prised its first ~discoverer, as on seeing
the flame pass over the surface ono
naturally thinks the drawing will bt
swamped and spoiled. Secondly, the
waxen picture, now apparently as per.
feet as it is white, is powdered all over
with black lead and polished with q soft
brush till it shines ike a guardsman'a
boot. Carefully, however, as it il
brushed, little specks of black lead re-
main loose in the interstices, and to get
rid of these a hose is now turned on to
the blackened surface, and the whole 10
rinsed and washed with cold water till
it is perfectly clean and ready for III
bath of D With this last and
most mysterious process we are, man9
of US, already familiar. Entirely sub
merged in a solution Of sulphuric acid
and copper and acted upon by a strong
electric current, to which the bright
metallic surface of the black lead offeri
good conducting medium, the waxeu
shape is soon found to be covered with
a coating of the purest copper, which,
initiating in the convex every interstics
of the matrix, offers as soon as it ID
strong enough to be removed-say, In
about three hours-a surface from
which, on an linked roller being passed
over it, a copy may be transferred to
paper of the drawing made by our deaf.
and-dumb friend upstairs with his
etching-needle on the flat wax. Such Is
the operation of topographic etching, az
seen by an uninstructed observer one
day last week at Chiswick.-Pdu Mall
Gdzene.